Male reproductive system

LECTURE FOR MEDICAL STUDENTS

DEPARTMENT OF HISTOLOGY,CYTOLOGY AND EMBRYOLOGY KhNMU

2012

The The internal male genitalia:internal male genitalia:

• the the testestestes

• the the epididymisepididymis, ,

• the the vas deferensvas deferens

• the the accessory sex accessory sex glands - glands - the seminal the seminal vesicles, vesicles,

the prostrate and the prostrate and

the bulbourethral glandsthe bulbourethral glands

FFunctions: unctions:

• Reproductive --- Reproductive --- produce the male produce the male gametes or spermatozoa, and gametes or spermatozoa, and

• Endocrine --- Endocrine --- produce male sexual produce male sexual hormonehormone ((testosteronetestosterone))

TestesTestes

The structure ofThe structure of Testes Testes

Connective tissue Connective tissue

• a thick capsulea thick capsule - - the the tunica tunica albugineaalbuginea

• the the mediastinummediastinum testistestis, projects into , projects into the testisthe testis and give and give septaeseptae

• Septae – divide testes Septae – divide testes on 200-250 lobuleson 200-250 lobules

Each Lobule consist of:Each Lobule consist of:

• Connective Connective tissue -- tissue -- Interstitium Interstitium -- with -- with Leidig cellLeidig cell

• SeminiferouSeminiferous tubules (1-s tubules (1-4 per lobule) 4 per lobule)

Leydig cellsLeydig cells (15-20 µm) (15-20 µm)

• synthesise and synthesise and secrete secrete testosteronetestosterone..

The Convoluted Seminiferous The Convoluted Seminiferous Tubules Tubules

CConsists of onsists of two types of two types of cells: cells:

•spermatogenispermatogenic cells c cells

•Sertoli cellsSertoli cells. .

Spermatogenic cellsSpermatogenic cells

• SpermatogoniaSpermatogonia - - Type A spermatogoniaType A spermatogonia - - Type B Type B spermatogoniaspermatogonia

• Primary spermatocytesPrimary spermatocytes

• Secondary spermatocytesSecondary spermatocytes

• SpermatidsSpermatids

• SpermatozoaSpermatozoa

SpermatogenesisSpermatogenesis

• Type A Type A spermatogoniaspermatogonia are are stem cellsstem cells

• which divide to which divide to form new form new generations of generations of spermatogonia.spermatogonia.

SpermatogenesisSpermatogenesis

• Type B Type B spermatogonia spermatogonia ------

their final mitosis their final mitosis always results in always results in the formation of the formation of Primary Primary spermatocytesspermatocytes

• Primary Primary spermatocytes spermatocytes appear larger than appear larger than spermatogonia. spermatogonia.

• They immediately They immediately enter the prophase enter the prophase of the of the first meiotic first meiotic divisiondivision, which is , which is extremely extremely prolonged (about 22 prolonged (about 22 days!). days!).

• The completion of The completion of the first meiotic the first meiotic division results in division results in the formation of the formation of Secondary Secondary spermatocytesspermatocytes

• Secondary Secondary spermatocytes, spermatocytes, are smaller than are smaller than primary primary spermatocytes. spermatocytes.

• They rapidly enter They rapidly enter and complete the and complete the second meiotic second meiotic division.division.

• Their division Their division results in the results in the formation of formation of Spermatids, Spermatids, which lie in the which lie in the luminal part of the luminal part of the seminiferous seminiferous epithelium. epithelium.

• The terminal phase The terminal phase of spermatogenesis of spermatogenesis is called is called spermiogenesisspermiogenesis

• and consists of the and consists of the differentiationdifferentiation of the of the newly formed newly formed spermatids into spermatids into SpermatozoaSpermatozoa

SpermatogenesisSpermatogenesis

• Cell divisions are Cell divisions are incomplete. The incomplete. The cells remain cells remain connected by connected by bridges of bridges of cytoplasm. cytoplasm.

Structure of spermatozoaStructure of spermatozoa

Sertoli cellsSertoli cells

• - - provide mechanical provide mechanical support for the support for the spermatogenic cells.spermatogenic cells.

• ---- provide provide blood-blood-testis barriertestis barrier..

• ------ have a nutritive have a nutritive function.function.

Eccurrent ductsEccurrent ducts

• MRS consists of MRS consists of DUCTSDUCTS

epididymis epididymis - - anatomyanatomy

• The The headhead of the of the epididymisepididymis receives the efferent ductules.  receives the efferent ductules.  

• The The tailtail of the of the epididymisepididymis leads leads into the into the vas deferens.  .  

efferent efferent ductulesductules

EpididymisEpididymis

ductus epididymidisductus epididymidis

It is lined by a very It is lined by a very tall pseudostratified tall pseudostratified columnar columnar epitheliumepithelium::

• principal cellsprincipal cells, , ((have have long stereocilialong stereocilia) )

• basal cellsbasal cells

ductductusus epididymisepididymis

• The The epididymal epididymal ductduct is extremely is extremely long (4 to 5 long (4 to 5 meters) but is meters) but is highly convoluted highly convoluted

•   ItIt is surrounded by is surrounded by smooth muscle and smooth muscle and embedded within a embedded within a loose, vascular loose, vascular stroma.stroma.

Male Accessory Reproductive Male Accessory Reproductive Glands Glands

Seminal Vesicles Seminal Vesicles

Seminal Vesicles Seminal Vesicles functionsfunctions::

• the formation of the formation of the sperm the sperm coagulum, coagulum,

• the regulation of the regulation of sperm motility and sperm motility and

Male Accessory Reproductive Male Accessory Reproductive GlandsGlands

Prostate• is the largest is the largest

accessory sex gland in accessory sex gland in men (about 2 x 3 x 4 men (about 2 x 3 x 4 cm). cm).

• The secretion contains The secretion contains citric acid, the enzyme citric acid, the enzyme fibrinolysin , acid fibrinolysin , acid phosphatase, a phosphatase, a number of other number of other enzymes and lipids. enzymes and lipids.

Male Accessory Reproductive Male Accessory Reproductive Glands Glands

• It contains 30 - 50 It contains 30 - 50 tubuloalveolar tubuloalveolar glandsglands, which , which empty into 15 - 25 empty into 15 - 25 independent independent excretory ducts. excretory ducts. These ducts open These ducts open into the into the urethraurethra. .

• tthe peripheral zone he peripheral zone contains large, so-contains large, so-called called mainmain glands glands, , whose ducts run whose ducts run posteriorly to open posteriorly to open into the urethra. into the urethra.

• tthe internal zone he internal zone consists of the so-consists of the so-called called submucosal submucosal glandsglands, whereas , whereas

• the innermost zone the innermost zone contains contains mucosal mucosal glandsglands. .

Male Accessory Reproductive Male Accessory Reproductive Glands Glands

• The glands are The glands are embedded into a embedded into a fibromuscular fibromuscular stroma, which stroma, which consists of smooth consists of smooth muscle and muscle and connective tissue connective tissue rich in collagenous rich in collagenous and elastic fibres. and elastic fibres.

Male Accessory Reproductive Male Accessory Reproductive Glands Glands

• The epithelium is The epithelium is cuboidal or cuboidal or columnar. columnar.

Prostate