THE ANATOMY AND HISTOLOGY OF

ORNITHODOROS CONCANENSIS

by

CHARLENE OLIVIA REAST, B.S. in H.E,

A THESIS

IN

ZOOLOGY

Submitted to the Graduate Faculty of Texas Tech University in

partial Fulfillment of the Requirements for

the Degree of

MASTER OF SCIENCE

Approved

ACKNOWLEDGME TS

I am deeply indebted to Dr. John E. George for

his patient counseling, encouragement, and direction

of this thesis and to the other members of my

committee. Dr. Earl D. Camp and Dr. R. W. Strandtmann,

for their helpful criticism.

11

TABLE OF CONTENTS

ACKNOWLEDGMENTS ii

LIST OF ILLUSTRATIONS iv

I. INTRODUCTION 1

II. MATERIALS AND METHODS 3

III. RESULTS AND DISCUSSION 5

The Alimentary System 5

The Reproductive System 15

The Excretory System 23

The Circulatory System 24

The Nervous System 25

The Respiratory System 27

ILLUSTRATIONS 30

LITERATURE CITED 63

APPENDIX 66

« • •

111

LIST OF ILLUSTRATIONS

Figure Page

1. Lateral view of mouthparts 32

2. Cross sections of capitulum 34

3. Cross sections of capitulum 36

4. Cross sections of capitulum 38

5. Drawing of midgut diverticula 40

6. Photomicrographs of diverticula, salivary

glands, stomach, brain 42

7. Drawing of male reproductive system . . . . 44

8. Drawing of accessory gland of male . . . . 46

9. Photomicrographs of male accessory gland and testis 48

10. Photomicrographs of ejaculatory duct, male accessory gland, genital aperture of male and ovary of female 50

11. Drawing of female reproductive system . . . 52

12. Photomicrographs of vagina 54

13. Photomicrographs of genital aperture of female. Gene's organ and coxal glands 56

14. Drawing of excretory and nervous systems 58

15. Photomicrographs of haemocytes, brain and spiracle 60

16. Drawing of tracheal system 62

IV

CHAPTER I

INTRODUCTION

This paper is a study of the internal morphology

and histology of Ornithodoros concanensis Cooley and Kohls,

1941.

Because of their medical importance, the ticks

have been studied overall more intensively than any other

group of acarines. Considerable attention has been directed

toward elucidation of the details of tick morphology and

histology. Ixodidae have been the subjects of the majority

of such studies. Particularly notable among these are the

comprehensive studies by Till (1961) of Rhipicephalus

appendiculatus and by Douglas (1943) of Dermacentor

andersoni. The only Argasidae that have been the subject

of comprehensive studies are Arqas persicus (Robinson and

Davidson 1913a, 1913b, 1914) and Ornithodoros kelleyi

(Sonenshine and Gregson 1970; Sonenshine 1970). Other

individual studies have been made of various organs and

systems of argasid ticks. The mouthparts of Ornithodoros

moubata were studied by Bertram (1939) and of Dermacentor

andersoni by Gregson (1960). True (1932) reported on the

alimentary canal of Ornithodoros coriaceus and Tatchell

(1962) did detailed work on the digestive system of Arqas

persicus. Tatchell (1964) also investigated the male

accessory gland of A^ persicus both histologically and

1

cytochemically. The egg-waxing organ in 0_j_ moubata

received the attention of Lees and Beament (1948) and

Lees (1946) described the chloride regulation and function

of the coxal glands in the same tick. The spiracle of

O. moubata was studied by Mellanbey (1935) and by Browning

(1954).

O. concanensis was described from specimens

collected in a cave near Concan, Uvalde County, Texas.

Since that time it has been collected from other caves and

also from around the nests of the cliff swallow

(Petrochelidon pyrrhonata). In the laboratory this tick

feeds readily on a variety of animals, including bats,

birds, rats, rabbits and man (George, pers. commun.).

In nature its hosts are probably bats and birds more

commonly than other animals. This tick is not known to

vector any diseases, but because of its broad distribution

and low degree of host specificity, it probably is involved

in the ecology of one or more zoonoses. Because it is a

relatively common parasite and its biology is being studied

at Texas Tech University from other aspects, it is a good

candidate for a study of tick histology. 0_ kelleyi is

the only other Ornithodoros species that has been the

subject of a detailed study of the type reported in this

paper.

CHAPTER II

MATERIALS AND METHODS

O. concanensis adults were secured from cliff

swallow nests located on the banks of the Double Mountain

Fork of the Brazos River southeast of Justiceburg, Garza

Co., Texas.

For the study of the gross anatomy, adult ticks

were secured in paraffin and dissections were done in 70%

ETOH to fix the delicate organs. Staining with Delafield's

haemotoxylin aided in the visualization of semi-

transparent structures.

For histological work specimens were fixed by

immersing them in Carney's acetic acid fixative for 24 hrs.

Slits were made in the dorsal cuticle of some specimens

to assure proper penetrations of the fixative; in others

the entire dorsal cuticle was removed. Following fixation

specimens were dehydrated for 24 hrs in each of the

following solutions: (1) 65 ml of 77% ETOH and 35 ml of

100% n-butyl alcohol, (2) 45 ml of 90% ETOH and 55 ml of

100% n-butyl alcohol, (3) 25 ml of 90% ETOH and 75 ml of

100% n-butyl alcohol, (4) 100% n-butyl alcohol. Following

dehydration the specimens were infiltrated in a mixture

of 2 parts paraffin and 1 part 100% n-butyl alcohol,

covered, and allowed to remain for 48 hrs in an oven at

63 C and then uncovered and kept in the oven for an

additional 24 hrs. The ticks were embedded in 100%

paraplast (56-57 C melting point) and sectioned at 7 or 10

microns. The slides were stained using Mayer's hemalum-

eosin technique.

CHAPTER III

RESULTS AND DISCUSSION

The Alimentary System

For convenience, the alimentary system of 0.

concanensis is divided into the following parts (Robinson

and Davidson 1913b, Sonenshine and Gregson 1970):

1. Mouthpart s.

2. Foregut; consisting of pharynx, oesophagus

and proventriculus.

3. Midgut; consisting of stomach with its

diverticula, rectal tube, and rectal sac.

4. Hindgut; consisting of anal canal and anal

aperture.

The above order will be followed in the descriptions of

the alimentary system.

The Mouthparts (Fig. 1-4). The mouthparts consist

of the palps, the hypostome, the chelicerae, the labrum,

the labial plate, and the salivary glands. A reconstruction

of the mouthparts of 0_ concanensis based on sagittal

sections is shown as Fig. 1.

At the anterior end of the capitulum, the hypostome

(HYP.), chelicerae (CH.), and palps (PALP) form the

preoral canal (PR. C.) which continues backwards eventually

connecting to the pharynx (PH.). The hypostome, forming

5

the ventral portion of the canal, is solid cuticle distally

with a smooth slightly concave dorsal surface. More

proximally the hypostome becomes hollow forming a

hypostomal cavity (Fig. 1, HYP. CAV.) that is continuous

with the body cavity. The hypostomal gutter (HYP. G.),

a groove in the dorsal surface of the hypostome which

deepens posteriorly into the form of a "V", empties into

the pharynx (Fig. 3A). A pair of dilatory muscles

(DIL. PR. C.) that originate on the floor of the hypostome

insert on the sides of the hypostomal groove (Fig. 3A) .

The labrum and more posteriorly the labial plate extend

through the preoral canal (PR. C.) dividing it into a

dorsal salivarium (SAL.) and a more ventral food channel

(Fig. 1). From the lateral aspect, the labrum appears as

a slender rod that extends forward from the anterior portion

of the pharynx almost the entire length of the hypostome

(Fig. 1). In cross section the labrum, except for its

distal end, has the appearance of a somewhat flattened

triangle with 3 strongly sclerotized internal ribs

(Fig. 2A, B). Medially the labrum fuses with the more

heavily sclerotized labial plate (Fig. 3A). Ventrally

the labrum and labial plate are in turn joined to the

dorsal surface of the hypostomal groove (Fig. 3B, 4A) as

the food channel becomes the triangular-shaped pharynx

(Fig. 3A). The antero-dorsal surface of the labial plate

forms the anterior floor of the salivarium (Fig. 1, 3A) .

"S.

A thin layer of cuticle extends from the posterior end of

the salivarium, forming the remainder of its floor, and

attaches to the labial plate forward of its posterior end.

The small space between this membrane and the labial plate

is termed by Sonenshine and Gregson (1970) the "labial

sac" (Fig. 1, 3B, LAB. SAC). The roof of the salivarium

is formed by the ventrally fused outer cheliceral sheaths

(Fig. 3A, B, O. CH. SH.). The labrum is similar to that

described for O ^ kelleyi and 0_ denmarki (Sonenshine and

Gregson 1970). In contrast to the very short labrum

present in D^ andersoni (Gregson 1960), the labrum in

O. concanensis is a very long one covering the food channel

almost its full length. Robinson and Davidson (1913b),

True (1932), and Bertram (1939) describe the labrum as a

short, cuticularized, tongue-like flap located anterior

to the pharyngeal orifice. It is suggested by Sonenshine

and Gregson (1970) that in O^ kelleyi and O^ denmarki the

labrum acts as a pre-pharyngeal valve activated by hydrostatic

pressure with dilation of the pharynx and preoral canal

creating the negative pressure necessary to suck blood and

other fluids from the host.

The chelicerae (Fig. 1) lie within the cavity of

the basis capituli (B. CAP.) dorsal to the labrum, labial

plate and salivarium with the proximal halves projecting

into the body cavity. The chelae (CH. DI.), located at

the distal extremity of the shaft of each chelicera.

"S.

8

consists of a freely articulated dentate digit in a

ventral position and a more dorsal fixed digit. Each

movable digit is controlled by 2 tendons lying in highly

sclerotized grooves in the cheliceral shafts as in A.

persicus (Robinson and Davidson 1913a); the large ventrally

located flexor tendon (FL. CH. DI.) and the more dorsally

situated extensor tendon (EXT. CH. DI.). The outer sheath

surrounds each chelicera (Fig. 2A) and extends from the

cheliceral digits to a point about half the length of the

cheliceral shaft before it fuses to become a dorsal and

ventral plate. Dorsally the outer cheliceral sheath

becomes continuous with the tectum (Fig. 1, 2B, TE.).

Ventrally it extends backward the length of the chelicerae

forming the roof of the salivarium and the area where the

bulbs of the chelicerae (CH. B.) rest on it is known as

the "sub-cheliceral plate" (Fig. 3A, SUB. CH. PL.). The

inner cheliceral sheaths (Fig. 1, I. CH. SH.), membranous

in form, arise at about the point where the outer

cheliceral sheath fuses dorsally with the tectum while

ventrally becoming so closely applied as to fuse to the

cheliceral bulb near its posterior end. The chelicerae

slide back and forth in their sheaths but are prevented

from rotating by their slightly flattened median surface

(Robinson and Davidson 1913a). The greatly enlarged,

bulbous cheliceral lobes are located posterior to the

shafts. Retractory muscles (Fig. 1, RETR. CH.) are

inserted on the external dorsal surface of the chelicerae.

The paired salivary glands, (Fig. 6B, 11), creamy

white clusters of glandular tissue somewhat grape-like in

appearance, occupy an antero-lateral position in the body

cavity, extending from the basis capituli laterally along

the body wall almost to the spiracles. They are scarcely

visible from above because they are almost entirely

concealed by the antero-lateral diverticula. Two types of

alveoli are present in these structures. Approximately

2/3 of the gland is composed of Type 1 alveoli (Fig. 6B,

SAL. GL. A. I.) with the remaining 1/3 Type II alveoli

SAL. GL. A. II). Type I alveoli consist of grape-like

clusters of 4 to 5 cells with large nuclei confined to the

basal region of each cell. These clusters are connected

to the main salivary duct (SAL. D.) by short secondary

branches (SAL. D'.). The cytoplasm of these cells appears

to be filled with numerous large granular masses some of

which stain red, some dark blue, while others are light

blue. Robinson and Davidson (1913b) explain that this

represents stages these cells go through in a regular

secretory cycle. The light blue staining cells are

considered to be in the earliest stages while the red and

most granule-laden cells are considered to be in the final

stages. Type II alveoli lie very close to the main

salivary duct. In each cell there are numerous fibrils

10

radiating toward the lumen and apparently ending free.

Four to 5 oval shaped nuclei are located at the distal

ends of these cells with one always much larger than the

others. The cell membranes are not visible. These 2

types of alveoli were reported for A^ persicus (Robinson

and Davidson 1913a), for D^ andersoni (Douglas 1943), and

for g_ kelleyi (Sonenshine and Gregson 1970) . Till (1961)

described 4 types of alveoli in the salivary glands of

Rhipicephalus appendiculatus with 5 cell types represented

in the granule secreting alveoli which are similar to the

Type I alveoli in argasid ticks.

There has been much speculation about the nature of

the salivary secretions of ticks. Gregson (1960) reported

2 types of materials produced by D_ andersoni while

feeding; a milky white latex-like material that serves to

cement the tick's mouthparts to the host's skin and a

clear fluid anticoagulant secreted at intervals during the

period of engorgement. Argasid ticks undoubtedly secrete

an anticoagulent, but because they remain attached to the

host for such a short time a cementing material would

appear to be unnecessary. Perhaps the secretions of

Type II alveoli in argasid ticks have a histolyzing or an

anesthetizing effect on the host's tissue.

The salivary ducts (Fig. 4A,B) enter the salivarium

at its posterior lateral margins. The main salivary

ducts lie ventro-lateral to the chelicerae. They pass

11

through the capitular foramen into the body cavity and

extend the length of the gland, receiving the secondary

branches along their route. The alveoli are arranged in

grape-like clusters and open into the system either

directly or by means of short, secondary branches (Fig. 6B)

The salivary ducts and the secondary branches are lined

with a spiral thickening of chitin and covered with a thin

membrane of squamous epithelial cells.

Foregut (Fig. 1, 6D). The long, fusiform pharynx

(Fig. 1, PH.) occupies a ventral position in the basis

capituli and connects the preoral cavity with the

oesophagus. In cross section the apices of the triangular

shaped pharynx are bifurcate and the structure assumes the

form, described by Robinson and Davidson (1913b), of a

Maltese cross with 3 arms (Fig. 4B). Dilator muscles that

insert on the walls of the pharynx (Fig. 4B, DIL. PH.)

originate on the sub-cheliceral plate and the walls between

the palps and the hypostome. Constriction of the pharynx

is accomplished by constrictor muscles (CON. PH.) attached

between the apices of the pharyngeal walls to form bands

around the pharynx. The arrangement of the muscles on the

pharynx are evidence of its function as a pumping organ.

The pharynx has a cuticular lining with a layer of squamous

epithelium underneath.

The oesophagus (Fig. 6D, OE.) extends from the

posterior end of the pharynx to the stomach (STOM.).

12

Departing the pharynx, it curves ventrally and then turns

dorso-laterally to pass through the central nerve mass

(Fig. 6D, C. N. S.) at an oblique angle, finally terminating

on the antero-median end of the stomach near its ventral

surface. The oesophagus is constructed of cuboidal

epithelial cells surrounded by a muscle layer. Robinson

and Davidson (1913b) described a chitinous lining for the

oesophagus and also for the proventriculus of A^ persicus,

but there was no evidence of cuticle present in 0_ kelleyi

(Sonenshine and Gregson 1970) and this was also true for

O. concanensis.

The proventriculus (Fig. 6D, PROV.) is formed by

a mass of columnar epithelial cells that protrude from the

distal end of the oesophagus into the lumen of the stomach.

It functions as a valve to prevent the backflow of the

stomach contents into the oesophagus.

Midgut (Fig. 5). The stomach occupies a median

dorsal position in the body cavity and has 3 diverticula

branching from each side of it. It is joined anteriorly

by the oesophagus and from its postero-ventral surface the

rectal tube (R. T.) connects it to the rectal sac (R. S.).

The stomach with its attendant diverticula, almost obscures

the other organs in the body cavity. Extending from a

position dorsal to the central nerve mass where it forms

a bulb-like protrusion, it terminates just dorsal to the

anus. The diverticula vary in shape depending upon the

13

amount of material present in them. On each side of the

stomach there are paired anterior diverticula (A. LAT. DIV.,

A. MED. DIV.), a single lateral diverticulum (LAT. DIV.),

and paired posterior diverticula (P. LAT. DIV., P. MED.

DIV.).

Sonenshine and Gregson (1970) found 5 primary and

several secondary diverticula in 0_ kelleyi. Roshdy

(1961, 1962) found 3 pairs of primary diverticula with

secondary branches and 1 unpaired antero-median diverti­

culum in A^ vespertilionis and A^ boueti, but found that

the diverticula of A_ transgariepinus (1963) and A.

brumpti (1966) resembled A^ persicus (Robinson and

Davidson 1913b) with only 3 pairs of diverticula, the

unpaired median lobe missing.

All of the ticks examined had fed recently and

active digestion was probably occurring when they were

fixed for sectioning. Three types of epithelial cells

(or, perhaps more accurately, cells in 3 different physio­

logical stages) were observed; namely, undifferentiated

cells, secretory cells, and columnar digestive cells

(Fig. 6A). The undifferentiated cells are cuboidal in

shape. The secretory cells are finger-like columnar cells

with vacuolated distal ends. The cytoplasm and nuclei are

confined to the basal areas. The columnar digestive cells

are filled with masses of granules in their swollen distal

ends which tend to strain brownish black. The nuclei are

-V

14

located at the proximal end near the basement membrane.

Fragments of these cells are seen floating free in the

lumen, suggesting they break off when filled with the end

products of digestion. Some digestive cells are almost

oval in shape and are filled with red staining granules.

Sonenshine and Gregson (1970) describe 3 types of

gut epithelial cells in 0_ kelleyi—digestive cells,

secretory, and undifferentiated reserve cells. Tatchell

(1964) distinguishes only 2 types of cells in A^ persicus,

undifferentiated interstitial and active epithelial cells

which undergo a regular cycle of secretory, absorptive

and intracellular digestion. True (1961) found this same

condition in 0_ coriaceus.

The S-shaped rectal tube (Fig. 6C) narrows somewhat

down its short length from the postero-ventral surface of

the stomach to its connection to the antero-median surface

of the rectal sac. Cuboidal epithelial cells line it;

squamous epithelial cells line the rectal sac. The

bilobed rectal sac (Fig. 6C, 13C) which is translucent and

membrane thin may be either white in appearance due to

the presence of masses of guanine crystals within it or

almost completely black with haematin interspersed with

guanine crystals (GU). Sonenshine and Gregson (1970) found

the rectal sac to be almost always white with just an

occasional specimen having black contents. The opposite

was found to be true in O. concanensis. The difference

15

was probably due to the physiological states of the ticks

used in these studies. The rectal tube enters the lower

median end of the rectal sac and the Malpighian tubules

attach at its antero-lateral margins (Fig. 13C). No

muscles were observed around the rectal tube as was

reported by True (1961). Sonenshine and Gregson (1970)

also noted the absence of muscles.

The Hindgut (Fig. 9B). The anal canal (A. C.) and

anal aperture (AN. AP.) comprise the hindgut. Both of

these have a cuticular lining. The anal canal, located

in an antero-ventral position on the rectal sac, is a

short, narrow, twisted passageway leading to the anus.

Squamous cells compose the outer epithelium of this

structure. Dilation of the canal is presumed to be

accomplished by the anal muscles located on either side.

The Reproductive System

The Male Reproductive System (Fig. 7,8) includes

a single testis, the vasa deferentia, the seminal vesicles,

the accessory gland, the ejaculatory duct, and the genital

aperture.

The long single testis (Fig. 7, T.) lies posterior

to the rectal sac and ventral to the posterior diverticula

of the stomach. The lateral extremities of this structure

are greatly thickened and the median portion or isthmus is

narrow. In a few specimen the lobes of the testis were

16

spiral shaped. A single testis was also reported for

O. kelleyi (Sonenshine 1970), A^ persicus (Robinson and

Davidson 1914), A^ vespertilionis (Roshdy 1963), A^ boueti

(Roshdy 1962), A^ transgariepinus (Roshdy 1963), and

A. brumpti (Roshdy 1966). However, Douglas (1943)

observed paired testes in the Ixodid tick D^ andersoni.

The testis consists of a layer of large cells surrounded

by a squamous epithelial layer. These large cells,

spermatocytes (Fig. 9C, SPERMAT.), observed only in the

lateral regions of the testis, contain large oval nuclei

and dark blue staining nucleoli. Spermatozoa (Fig. 9A,

SPERMAT'.), elongated cells having their double membranes

indented near one end, were observed in large numbers in

the vasa deferentia and in the seminal vesicles.

The paired vasa deferentia (Fig. 7, V. D.),

thickened somewhat where they connect to the testis,

rapidly become thinner before connecting to the sac-like

seminal vesicles (S. V.). Located in a median position

between the dorsal and ventral granular lobes of the

accessory gland, the paired seminal vesicles are not

visible dorsally but can be observed from a lateral view

(Fig. 8). These organs open into the ejaculatory duct

(Fig. 9A, E.D.). Sonenshine (1970) reported paired

seminal vesicles for 0_ kelleyi. Robinson and Davidson

(1914) noted a single seminal vesicle as the terminal

point for the vasa deferentia in A^ persicus, and Roshdy

- ^ v

17

(1961, 1962, 1963, 1966) found this condition true in the

4 species of ticks he studied. Both the vasa deferentia

and seminal vesicles consist only of a thin layer of

squamous epithelium.

The ejaculatory duct (Fig. lOA, E.D.) is a short

passageway leading to the outside of the exoskeleton

through the genital aperture (GEN. A.). Passing ventrally

toward the central nerve mass, this broad, more or less

flattened tube, has a heavily cuticularized inner lining

overlaid with a layer of cuboidal cells. Two pairs of

muscles insert on the dorsal and ventral surfaces of the

duct. The seminal vesicles open into it dorsally while

it receives the ducts of the accessory glands laterally,

posteriorly and ventrally (Fig. lOA).

Situated in a median position in the body cavity,

the large accessory gland (Fig. 7, 8), is composed of 8

granular lobes and 1 spongy lobe. The large antero-dorsal

granular lobe (ANT. D. G. L.) is almost bilobed in

appearance due to a median groove running its full length

plus indented anterior and posterior ends. The anterior

portion of this lobe communicates directly with the seminal

vesicles and its postero-ventral surface is fused to the

ventral granular lobe (V. G. L,). The ventral granular

lobe constitutes the major portion of the accessory gland

with its anterior portion ventral to the ejaculatory duct

(Fig. 10) and the remaining portion lateral and ventral

18

to the seminal vesicles. It communicates directly with

the seminal vesicles at their junction with the ejaculatory

duct (Fig. 10). The paired wing-shaped postero-dorsal

granular lobes (Fig. 8, 9, P. D. G. L.) attach in a median

position on the gland above the paired balloon-shaped

posterior granular lobes. Each lobe consists of squamous

epithelium covering a layer of greatly elongated columnar

cells filled with numerous granules. The granules of the

dorsal and ventral granular lobes are blue-staining and

densely packed while those of the posterior granular lobes

are stained pink and are more loosely packed. The paired

lateral granular lobes (Fig. 8, L. G. L.) are hidden from

view by the dorsal lobes. With somewhat transparent i

membranous coverings, these lobes differ from the dense, 5|

chalky white appearance of the others. They also differ

by having rather loosely packed, large orange-staining

granules instead of the smaller blue or pink-staining

ones. The paired spongy lobes (Fig. 8, SPO. L.), located

on the ventral surface and hidden from dorsal view by the

granular lobes, consist of large columnar cells devoid

of granules.

The accessory gland of O^ concanensis is similar

to that of 0jj_ kelleyi (Sonenshine 1970) in position and

total number of lobes. The lobes differ in shape and

arrangement with 0_ concanensis having paired postero-

dorsal, posterior and paired spongy lobes, whereas 0_

19

kellevi is reported to have 3 pairs of postero-lateral

lobes and a posteriorly bifurcated spongy lobe. Robinson

and Davidson (1914) found 8 granular lobes and 4 spongy

lobes in A^ persicus. This same number was reported by

Roshdy (1961, 1962, 1963, 1966) for the 4 species he

studied.

The principal organs of the female reproductive

system (Fig. 11) are the ovary, paired oviducts, the

uterus, the paired accessory glands, the vagina, the

genital aperture, and the Gene's organ.

The single ovary (O.) lies transversely just i X

posterior to the rectal sac and ventral to the posterior i m •g

portion of the stomach. The external surface is studded 2;

with the underlying spherical ova. The two lateral segments :^

narrow in the center and are encased in a very thin i

membrane of squamous epithelium. The ova in all stages

of development from oocytes to apparently mature ova of

varying size and shape occur scattered among many very

small unaltered cells (Fig. lOD). As the ova increase

in size, a pedicel is formed from the unaltered cells

(Fig. 11). Some ova show aggregations of yolk granules

in their cytoplasm with the nuclei spherical in appearance.

Some pear-shaped ova are seen with the pedicel attached

to the smaller end.

The paired oviducts (Fig. 11, OV.), long, winding

tubes of varying widths, issue from the antero-lateral

20

ends of the ovary. These tubes eventually pass along the

lateral walls of the uterus, ballooning perceptibly in an

area near the neck of the uterus and narrowing again

prior to an abrupt turn posteriorly across the lateral

margins of the uterus to enter this structure at its

postero-median end. The elongated sac-like portion of

the oviduct was noted by Roshdy (1961, 1962) for A.

vespertilionis and for A^ boueti. The relatively

thickened walls of the oviducts are composed of an inner

lining of very densely packed columnar cells with their

spherical nuclei located near the basement membrane, a i p •A middle layer of circular muscles and an outer squamous

epithelial layer. This type of cellular arrangement was g

described by Sonenshine (1970) for 0_ kelleyi and also for pi

A. persicus by Robinson and Davidson (1914) . ||

The large heart-shaped uterus (Fig. 10 C, U.),

lying in a median position in the body cavity below the

stomach proper, is partially divided at its proximal end

and narrows toward its distal end as it merges with the

vagina. It is composed of somewhat closely packed

columnar cells with basely located spherical nuclei and

overlaid with a squamous epithelial layer.

Robinson and Davidson (1913b) believe the uterus

functions as a seminal receptacle due to the presence of

spermatophores here in inseminated females. Sonenshine

21

(1970) supports this opinion having found as many as 5

spermatophores in O^ kelleyi females.

The vagina (Fig. 12A, B) extends from the uterus

to the external genital opening and is composed of a

cervical portion and a vestibular portion. The cervical

portion (Fig. 12A, VG.) is distinguished from the rest

of the genital tract by a thin internal sheath of chitin

which is continuous with the exoskeleton. One end of the

cylindrically shaped cervical portion of the vagina is

partially prolapsed into the cavity of the uterus forming

a rosette of tissue (Fig. 12B) which marks the opening of j p'

the narrow lumen of this structure. The other end turns '^

ventrally to open into the vestibular portion of the vagina. J

The cervical vagina is composed of an outer squamous W

epithelium, circular and longitudinal muscles, and an g

inner lining of tall columnar cells that is very deeply

folded longitudinally. The thick chitinous lining dips

down into the longitudinal folds. The vestibular portion

of the vagina (Fig. 12C, VG'.) is a broad flattened tube

which narrows markedly near its departure from the cervical

portion to widen once more on its way to the genital

aperture. Beneath the more thickened chitinous lining

of this portion of the vagina is a layer of large cuboidal

epithelial cells. A similar division of the vagina into

2 distinct portions was reported by Robinson and Davidson

(1914) for A^ persicus. Sonenshine (1970) found 2 regions

^

22

but unable to find evidence of cuticle in the cervical

portion, called this portion the vagina and labeled the

vestibular portion, with its cuticular lining, the

vestibule.

The accessory glands (Fig. IOC, 12C, ACC. G.) open

into the vestibular vagina shortly after its departure

from the cervical portion. The small sausage-shaped

accessory glands, lying adjacent to the dorsal surface of

the uterus, are composed of an inner epithelium of columnar

cel].s with basely placed spherical nuclei covered by a

thin outer layer of squamous cells. J

/ s. Gene's organ (Fig. IOC, 13B, G. O.), a multilobed

m structure located above the capitulum of the female, is xi

C separated from the rest of the female reproductive system. B'

This glandular organ consists of a pair of posterior <

lobes, each containing a glandular sac and a hypodermal

sac. The dorsally situated glandular sac (Fig. 13B,

GL. G. O.) is composed of tall columnar or large cuboidal

epithelial cells while the ventrally located hypodermal

sac (HD. S.) contains a collapsed, somewhat folded

chitinous lining (CT. L.) covered by a thin squamous

epithelium. This chitinous lined sac was described by

Robinson and Davidson (1914) but Sonenshine (1970) did not

find it present in 0_^ kelleyi. The Gene's organ functions

during oviposition to coat each egg with a wax to prevent

desiccation (Lees and Beament, 1949).

23

The Excretory System

Paired Malpighian tubules (Fig. 12C, 14, MAL. T.),

glistening white in appearance due to the presence of

guanine crystals and a white, cloudy fluid, are attached

to the antero-lateral margins of the rectal sac. Each

tube is more than one and one-haIf times as long as the

body of the tick and winds through the body before

terminating near the anterior end, dorsal to the notch of

the anterior diverticula of the stomach. The Malpighian

tubules are composed of an outer layer of squamous H

epithelial cells and an inner layer of cuboidal epithelial ,

cells. S

Paired sacular coxal glands (Fig. 13C, 14, COXAL C ^ •

» ' I

G.), occupy a position ventral to the salivary glands.

They lie between the coxal folds of the second coxae

opening into the basal space between legs I and II. The

alveoli are joined to the main duct by short, secondary

branches. The main duct and the secondary branches have

a cuticular lining supported by spiral thickenings. A

membrane of squamous cells surrounds the entire gland.

Argasid ticks feed so rapidly that evaporation of water

from the blood meal is not possible; therefore, following

a blood meal, the ticks excrete about half of the ingested

water in the coxal fluid (Lees 1946).

<

24

The Circulatory System

The balloon-shaped heart (Fig. 5, HT.) occupies a

dorso-posterior position above the stomach proper. It is

secured in position by a network of connective tissue.

The shallow cavity of the heart is surrounded by a layer

of squamous epithelium. The aorta (AO.) leads from the

antero-median tip of the heart across the stomach and dips

ventrally between the anterior bulge of the stomach and

the antero-median diverticula. As it passes ventrally,

the aorta enlarges forming a sac which completely encom-

passes the central nerve mass. The space between the sac J s»

and the brain is known as the periganglionic sinus. By i ml

this means, the brain and anterior portion of the animal i' C

is supplied with blood pumped directly from the heart. Jl r

Douglas (1943) explains that in action the heart simply <

contracts in the manner of a clinching fist, the ostia

close automatically, and the blood is forced into the dorsal

aorta. The blood is an almost colorless fluid in which

numerous large ameboid corpuscles are suspended (Fig. 15).

These cells contain large dark-staining nuclei and have a

very reticulated cytoplasm. Robinson and Davison (1913b)

reported a system composed of a heart, arteries and a

periganglionic sinus for A^ persicus. A similar system

with the addition of a perioespohageal sinus was described

for D^ andersoni (Douglas 1943). There is no mention of

25

a circulatory system for R^ appendiculatus (Till 1961) or

for O^ kellevi (Sonenshine 1970).

The Nervous Svstem (Fig. 14)

The brain and the peripheral nerves leading from

it comprise the nervous system.

The brain (C. N. S.) is glistening white, almost

oval in shape, and lies dorsal to the genital aperture

and ventral to the stomach. The oesophagus passes through

the brain and demarcates the supra-oesophageal division

from the more ventral and posterior sub-oesophageal rrn

division. The brain is composed of an outer ganglionic

layer and an inner layer of fibers. The whole is completely

9 V>> HI If*

r surrounded by a very thin sheath of squamous epithelial 5'

cells. g!

The ganglionic layer as seen in cross section is

composed of several distinct ganglia—the paired palpal

ganglia, the paired cheliceral ganglia, 4 pairs of pedal

ganglia and 2 pairs of visceral ganglia. The small palpal

ganglia are located in the antero-median region of the

supra-oesophageal division of the central nerve mass with

the small cheliceral ganglia in the lateral region of

this division. The 4 large pedal ganglia are located in

the lateral regions of the sub-oesophageal division. The

small visceral ganglia occupy an antero-lateral position

in the sub-oesophageal division.

26

The peripheral nervous system (Fig. 14) is composed

of the pharyngeal, cheliceral, palpal, pedal, and visceral

nerves. The pharyngeal nerves (PH. N.) lie immediately to

the side of the oesophagus, extending to the basis

capituli and then to the muscles of the pharynx. The

cheliceral nerves (CH. N.) arise from the anterior margin

of the supra-oesophageal division of the brain and lead to

the cheliceral bases. The palpal nerves (P. N.) depart

the brain at the antero-lateral margins of the supra-

oesophageal division and enter the basis capituli to

enervate the palps. The 4 large pedal nerves (PED. N. I-IV) ^.

extend from the lateral margins of the central nerve mass ^ HI

to the 4 pairs of legs. Two pairs of small lateral S SI

visceral nerves (VISC. N.) extend postero-laterally from C &

the end of the sub-oesophageal division and are assumed £>'

to enervate the viscera. One pair of branched medially

located visceral nerves (VISC.N'.) depart the sub-

oesophageal division of the brain in a postero-median

position with the more central branch leading to the

rectal sac, the median branch to the posterior body

muscles, and the outer branch to the lateral body muscles.

The nervous system of 0_ kelleyi and O^ concanensis

differ in only 1 area; Sonenshine (1970) observed 1 pair

of visceral nerves in O^ kelleyi whereas 3 visceral

nerves, 1 pair and 1 branching nerve, were observed for

• \

27

O. concanensis. Robinson and Davidson (1914) reported

7 pairs of main trunk nerves in A^ persicus.

The Respiratory System (Fig. 16)

The respiratory system consists of paired spiracles

and 8 branched tracheal trunks. The spiracles (Fig. 15C,

SP.) are raised areas of the integument lateral to the

junction of coxa III and IV. Each spiracle is composed of

a macula (MAC.) and a spiracular plate (SP. PL.) separated

by the slit-like spiracular opening, the ostium (OST.).

The crescent-shaped spiracular plate partially encircles JH, x'

a portion of the pad-like macula in its ventral location. yi> HI

In cross sections the thin pillar-like pedicels of the [?

spiracular plate are quite apparent (Fig. 15C). The C

structure of the spiracles of 0_ concanensis greatly £1 <\

resembles that of 0_ kelleyi (Sonenshine 1970) and A.

persicus (Robinson and Davidson 1913b).

Connecting the spiracles to the tracheal trunks

are the sac-like chambers of the atria (Fig. 15C, ATRIUM).

The atria have an inner lining of cuticle overlaid by a

cuboidal epithelium that is continuous with the epidermis.

The cuticular lining is continuous throughout the tracheal

system.

The number and arrangement of the tracheal trunks

in 0_j_ concanensis is very similar to that found by

Sonenshine (1970) in O^ kelleyi. There are 8 tracheal

trunks, 5 ventral and 3 dorsal. Roshdy (1961) reported

28

3 main tracheal trunks for A^ vespertilionis, 5 trunks for

A . transgariepinus (1963), and for A^ brumpti (1966)

but found only "tracheal bundles" in A^ boueti (1962).

Five trunks were also found in A^ persicus (Robinson and

Davidson 1913b).

The antero-lateral trunk (ANT. LAT. T.), largest

in the body, extends anteriorly to the chelicerae,

capitulum, salivary glands and coxal glands, then branches

to serve the central nerve mass and has 4 pedal tracheae

extending into the legs. The antero-median trunk

(ANT. MED. T.) subdivides to extend to the posterior H ml X

portion of the central nerve mass, the anterior portion ; HI

of the oviducts in the female and to the accessory gland g SI

and the anterior portion of the vasa deferentia in the c c?'

male. The antero-dorsal trunk (ANT. DOR. T.) and smaller P\

divisions extend along the dorsal integument and dorsal

ventral body muscles. The median trunk (MED. T.) sub­

divides to extend to the lateral portions of the gonads

and the rectal sac. The medial regions of the gonads are

served by the postero-median trunk (P. MED. T.). The

median dorsal trunk (MED. DOR. T.) serves the median portion

of the dorsal integument and the muscles of this area of

the body. The postero-dorsal trunk (P. DOR. T.) divides

to extend to the more posterior body muscles and midgut

diverticula. The postero-lateral trunk (P. LAT. T.)

branches more medially to serve the diverticula of the

29

midgut, ventral integument, and the dorso-ventral muscles

of the body.

K P'

HI

rs' SI c: 03] JO'

H ml X P' •»*

HI ILLUSTRATIONS [>

Si

c: C3]

i

31

H

X P' ifi^

HI

D' SI

JO'

Fig. 1. Lateral view of a reconstruction of the

mouthparts and related organs in

O. concanensis.

32

c/>

H ffll X P ' Vi<

HI ml s; r;

33

3'

8S| SI ei

Fig. 2.

A. Cross section of the capitulum at the

level of the palpal article.

B. Cross section of the capitulum near the

base of the hypostome.

34

O.CH.SH. I .CH .SH.

. . . C H . SH.

. t ^ . - - P A L P

HYP. - - L A B .

. C H . SH. SI

j a - - P A L P

- .HYP. G

HYP.

B o.imm

35

H •n t<

A •H t l

X

s

Fig. 3.

A. Cross section near the anterior region

of the pharynx and salivarium.

B. Cross section near the middle of the

salivarium.

36

TE

I . C H . S H . I

CH.SH.

-HYP . CAV.

CH.SH

I . C H . S H . I EXT. C H . D I .

FL .CH. DI.

SUB. C H . P L

B o.imm

37

Ik 91

Fig. 4.

A. Cross section at the opening of the

salivary duct into the salivarium.

B. Cross section near the middle of the

pharynx.

L - » . CH. SH.

38

AriV-DlL. PH.

-PH.

-CON. PH.

6 O.imm

39

H n <

A H 1% •5 .S

0 C

Fig. 5. Drawing of the gross anatomy of the

midgut diverticula in the adult

O. concanensis with the heart and

dorsal aorta in position.

40

ANT. MED. D IV .

ANT. LAT. D IV .

ANT. DIV.

AG.

S T O M .

HT.

1 . . . LAT. D I V .

. . . P . LAT. D I V .

P. M E D . DIV.

41

n <

C:

P

Fig. 6

A. Photomicrograph of a cross section through

the diverticula illustrating secretory and

digestive cells. X550

B. Photomicrograph of a longitudinal section

through the salivary glands showing Type I

alveoli and secondary salivary ducts;

Type II alveoli along the main salivary

duct. X200

C. Photomicrograph of a longitudinal section

through the posterior region of the stomach,

rectal tube, and rectal sac. Guanine

crystals are seen inside the rectal tube.

X200

D. Photomicrograph of the brain at the point

where the oesophagus passes through it to

enter the stomach. The valve-like

proventriculus is shown. X200

42

fl >% ^ A M OL} • • «#• -> M^* «««V «r<*^- J

43

H n <

>

H

Fig. 7. Drawing of the male reproductive system

of O^ concanensis/ dorsal aspect.

Hidden from view are lateral and ventral

granular lobes and spongy lobes.

44

. . . A N T . D. G. L.

. L / . - . P . 0. G. L.

_ . . P. G. L

o.sm m

45

1 < HI

y

y

c

Fig. 8. Drawing of the accessory gland of the

male O^ concanensiS/ lateral aspect.

46

P. 0. G. L. A N T . D.G.L.

P. G. L V. G. L.

S P O . L.

4i <

3'

-J

D.smm

47

4 y

9'

Fig. 9.

A. Photomicrograph of cross section through

male accessory gland near anterior region

illustrating a portion of the antero-dorsal

granular lobe, seminal vesicles, lateral

granular lobes and ventral granular lobe.

X200

B. Photomicrograph of cross section through

the postero-median section of the male

accessory gland illustrating the spongy

lobes, anal canal and anal aperture. X200

C. Photomicrograph of cross section through

lateral portion of testis. Packets of

spermatocytes are pictured. X550

48

L G/L

4

<

•J

49

•4 i < It y

4 1 >

i

i

Fig. 10

A. Photomicrograph of cross section through

anterior of ejaculatory duct where

antero-dorsal granular lobe, seminal

vesicles, lateral granular lobes, and

ventral granular lobes merge with the

ejaculatory duct. X200

B. Photomicrograph of genital aperture of

male. X200

C. Photomicrograph of cross section of ovary

illustrating ova in various stages of

development. X200

D. Photomicrograph of ovary showing pedicel.

X550

50

51

* '•I

Fig. 11. Drawing of the female reproductive

system; salivary glands.

52

o-smm

53

I tl * I I > 41 II

71

I

Fig. 12.

A. Photomicrograph of cross section of

cervical and vestibular portions of the

vagina. X200

B. Photomicrograph of longitudinal section

of cervical vagina showing rosette at

opening into uterus. X200

C. Photomicrograph of longitudinal section

of vestibular portion of vagina. Note

opening of accessory gland into this

portion (arrow). X200

54

B P ^

55

I, *

:i

i i

Fig. 13.

A. Photomicrograph of cross section of

genital aperture just inside vestibular

vagina. Note portion of central nerve

mass above. X200

B. Photomicrograph of cross section through

central portion of Gene's organ. Note

cuticular lining of hypodermal sac. X200

C. Photomicrograph of cross section of

coxal glands. X550

56

rrf-'^

I II 4 • i

II h

8

H It i!

57

!,

!l

Fig. 14. Drawing of the dorsal view of the

excretory system and nervous system of

Ornithodoros concanensis.

58

0-5m m

59

•I tl

9 !l

Fig. 15.

A. Photomicrograph of haemocytes (arrows)

in a female 0_ concanensis; longitudinal

section near the hypostome. X550

B. Photomicrograph of longitudinal section

of brain. Note aorta entering

periganglionic blood sinus surrounding

the brain. X200

C. Photomicrograph of cross section of

the spiracle. Note spiracular pedicels

(arrow). X550

60

61

•la

Fig. 16. Drawing of the tracheal system of

O. concanensis.

6 2

- _ J - - PED. TR.

ANT. LAT. T.

ANT. DOR. T.

ANT. MED. T.

SP.

MED. T.

P. MED. T. P. DOR. T.

MED. DOR. T.

P. LAT. T.

o.sm m

LITERATURE CITED

Bertram, D. S. 1939. The structure of the capitulum in

Ornithodoros: a contribution to the study of the

feeding mechanism in ticks. Ann. Trap. Med.

Parasit. 33: 229-58.

Browning, T. O. 1954. On the structure of the spiracle

of the tick Ornithodoros moubata Murray.

Parasitoloqv 44: 310-12.

Douglas, J. R. 1943. The internal anatomy of

Dermacentor andersoni Stiles. Univ. Calif. Pub.

Ent. 7: 207-72.

Gregson, J. D. 1960. Morphology and functioning of the

mouthparts of Dermacentor andersoni Stiles.

Acta. Trop. 17(1): 48-72.

Lees, A. D. 1946. Chloride regulation and the function

of the coxal glands in ticks. Parasitology 37:

172-184.

Lees, A. D., and J. W. L. Beament. 1948. An egg-

waxing organ in ticks. Quar. J. Micr. Sci.

89: 291-332.

Mellanby, K. 1935. The structure and function of the

spiracle of the tick Ornithodoros moubata Murray.

Parasitoloqv 27: 288-90.

63

64

Robinson, L. E., and J. Davidson. 1913. The anatomy of

Arqas persicus (Oken), 1818. Part I. Parasitoloqv

6: 20-48.

1913b. The anatomy of Arqas persicus (Oken), 1818.

Part II. Ibid. 6: 217-56.

1914. The anatomy of Arqas persicus (Oken), 1818.

Part III. Ibid. 6: 382-424.

Roshdy, M. A. 1961. Comparative internal morphology of

subgenera of Arqas ticks (Ixodoidea, Argasidae).

I. Subgenus Carlos: Arqas vespertilionis

(Latreille, 1802). J. Parasitol. 47(6): 987-94.

1962. Comparative internal morphology of subgenera of

Arqas ticks (Ixodoidea, Argasidae). 2.

Subgenus Chiropterarqas: Arqas boueti Roubaud

and Colas-Belcour, 1933. Ibid. 48(4): 623-30.

1963. Comparative internal morphology of subgenera of

Arqas ticks (Ixodoidea, Argasidae). 3. Subgenus

Secretarqas: Arqas transqariepinus White, 1846.

Ibid. 49: 851-56.

1966. Comparative internal morphology of subgenera

of Arqas ticks (Ixodoidea, Argasidae). 4.

Subgenus Oqadenus: Arqas brumpti Neumann, 1907.

Ibid. 53(4): 776-82.

Tatchell, R. J. 1962. Studies on the male accessory

reproductive glands and the spermatophore of the tick,

Arqas persicus Oken. Parasitoloqv 52(1,2): 133-32.

65

1964. Digestion in the tick Arqas persicus Oken.

Ibid. 54: 423-40.

Till, W. W. 1961. A contribution to the anatomy and

histology of the brown ear tick Rhipicephalus

appendiculatus Neumann. Mem. Ent. Soc. S. Africa

6: 1-124.

True, Gordon Haines, Jr. 193 2. Studies on the anatomy

of the Pajaroello tick, Ornithodorus coriaceus

Koch. 1. The alimentary canal. Univ. Calif.

Publ. Ent. 6(3): 21-48.

Sonenshine, D. E., and J. D. Gregson. 1970. A

contribution to the internal anatomy and histology

of the bat tick Ornithodoros kelleyi Cooley and

Kohls, 1941. I. The alimentary system, with

notes on the food channel in Ornithodoros denmarki

Kohls, Sonenshine, and Clifford, 1965. J. Med.

Ent. 7(1): 46-64.

Sonenshine, Daniel E. 1970. A contribution to the

internal anatomy and histology of the bat tick

Ornithodoros kelleyi Cooley and Kohls, 1941. II.

The reproductive, muscular, respiratory, excretory,

and nervous systems. J. Med. Ent. 7(3):

289-312.

APPENDIX

EXPLANATION OF ABBREVIATIONS USED IN TEXT FIGURES

A. C.

ACC. G.

A. LAT. DIV.

A. MED. DIV.

AN. AP.

ANT. DIV.

ANT. D. G. L.

ANT. DOR. T.

ANT. LAT. T.

ANT. MED. T.

AO.

ATRIUM

B. CAP.

CH. B.

CH. DIG.

CH. N.

CH. SH.

C. N. S.

CON. PH.

COXAL G.

CT. L.

DIG. CELL

DIL. PH.

DIL. PR. C.

Anal canal

Accessory gland of the female

Antero-lateral diverticulum

Antero-median diverticulum

Anal aperture

Anterior diverticulum

Antero-dorsal granular lobe

Antero-dorsal trunk

Antero-lateral trunk

Antero-median trunk

Aorta

Atrium

Basis capituli

Cheliceral base

Cheliceral digit

Cheliceral nerve

Cheliceral shaft

Central nervous system

Constrictors of the pharynx

Coxal gland

Cuticular lining of Gene's organ

Digestive cell

Dilators of the pharynx

Dilators of the preoral canal

67

68

E. D. Ejaculatory duct

Extensor of the cheliceral digit

Flexor of the cheliceral digit

Gene's organ

Genital aperture

Glandular portion of Gene's organ

Guanine spherules

Hypodermal sac of Gene's organ

Heart

Hypostome

Hypostome cavity

Hypostomal gutter

Inner cheliceral sheath

Labial plate

Labial sac

Labrum

Lateral diverticulum

Lateral granular lobe

Macula

Malpighian tubules

MED. DOR. T. Median dorsal trunk

MED. T. Median trunk

O. Ovary

O. CH. SH. Outer cheliceral sheath

OE. Oesophagus

OST. Ostium

EXT.

F L .

G. 0

GEN.

GL.

GU.

HD.

HT.

HYP.

HYP.

HYP.

CH. D I

CH. D I .

A .

G. 0 .

S .

CAV.

G.

I . CH. S H .

LAB.

LAB.

LAB.

LAT.

L . G

MAC.

MAL.

P .

SA.

D I V .

. L .

T .

69

OV. Oviduct

OVA Ova

PALP Palp

PED. N. I-IV Pedal nerves I-IV

PED. TR. Pedal trachea

PH. Pharynx

PH. N. Pharyngeal nerve

P. DOR. T. Postero-dorsal trunk

P. D. G. L. Postero-dorsal granular lobe

P. G. L. Posterior granular lobe

Postero-lateral diverticulum

Postero-lateral trunk

Postero-median diverticulum

Postero-median trunk

Palpal nerves

Pedicel of ovum

Preoral canal

Proventriculus

Retractors of the chelicerae

R. S. Rectal sac

R. T. Rectal tube

SAL. Salivarium

SAL. D. Salivary duct

SAL. D'. Secondary salivary duct

SAL. G. Salivary glands

SAL. G. A. I Salivary gland alveoli type I

P .

p .

p .

p .

p .

p .

PR,

LAT.

LAT.

MED.

MED.

N .

OV.

. c.

PROV.

DIV

T .

DIV

T .

RETR. CH.

70

SAL. G. A. II

SEC. CELL

SP.

SPERMAT.

SPERMAT'.

SP. P.

SPO. L.

STOM.

SUB. CH. PL.

S. V.

T.

TE.

U.

V.

V. D.

V. G. L.

VEST.

VISC. N.

VISC. N'.

Salivary gland alveoli type II

Secretory cell

Spiracle

Spermatocyte

Spermatozoa

Spiracular plate

Spongy lobe

Stomach

Sub-cheliceral plate

Seminal vesicle

Testis

Tectum

Uterus

Vagina, cervical portion

Vas deferens

Ventral granular lobe

Vestibular portion of vagina

Lateral visceral nerves

Medial visceral nerves