J. Anat. Lond. (1964), 98, 8, pp. 365-376 365With 11 plates and 2 text-figuresPrinted in Great Britain

Radiographic studies of the renal portal system inthe domestic fowl (Gallus domesticus)

By A. R. AKESTERSub-Department of Veterinary Anatomy, University of Cambridge

INTRODUCTION

Although a considerable amount of research has been devoted to the avian renalportal system during the past 150 years, its physiological significance and thefactors which control its function are still far from being well understood.A useful summary of the earlier work on this subject is given by Sperber (1948),

who is probably the first person to present clear experimental evidence that therenal portal system can function in birds. He has injected phenol red into one legand, after cannulation of the ureters, found that more phenol red is excreted by theipsilateral than by the contralateral kidney.More recent work has shown that the isolated renal portal valve of turkeys, when

placed in a bath of oxygenated Tyrode's solution, responds to autonomic drugs.Acetylcholine and histamine cause contraction, whilst adrenaline and noradrenalinecause relaxation of the histamine-contracted valve (Rennick & Gandia, 1954).Further support for the belief that autonomic nerves control the opening and closingof the renal portal valve is presented by Gilbert (1961), who mounted and stainedwhole valves and showed that the smooth muscle, which is confined to the basaltwo-thirds of the valve, receives a considerable nerve supply. This he presumes to beautonomic.

So far no information has been published which describes direct observations ofthe portal blood as it actually flows through the kidney in the living bird, or of theeffect that opening and closing of the renal portal valve has on this flow.The present work has been carried out to provide this information and also to

study variations in the route taken by renal portal blood, resulting from the activityof the renal portal valve.

MATERIALS AND METHODS

Healthy mature cockerels, of various breeds, were used for these studies. In sixbirds rubber latex casts were made of the entire venous system. Fifty renal portalvalves were examined. Over 100 still radiographs and several hundred feet of cinefilm were exposed to show the route taken by radiopaque material as it flowedthrough the kidneys of forty different birds.

Rubber latex casts. This method of obtaining an accurate replica of all the veinsthat are associated with the renal portal system was found to be extremely helpfulfor the interpretation of the radiographs. The bird was anaesthetized by injecting25 % urethane solution into a wing vein. The hip joint was dislocated to facilitateexposure of the external iliac vein, which was then cannulated. Heparin was in-jected and as much blood as possible was allowed to flow from the cannulated vein.

This was found to be a better method of bleeding the bird than by using the femoralartery.The cannula was then connected to an injection apparatus and rubber latex

(Revertex with Monolite fast yellow dye) was pumped into the venous system at apressure of about 15 lb./sq. in. When an appropriate amount had been injected thecannula was tied and the bird (after plucking) was placed in a bath of concentratedhydrochloric acid. After 48 hours the cast was removed from the acid, washed care-fully and allowed to dry. The main advantage of rubber latex for this type of work,over more brittle material (Marco resin), lay in its useful combination of flexibilitywith adequate rigidity. No significant difference was detected in the arrangementof veins from the six birds that were studied in this way.

Dissection ofthe renal portal valve. To expose the valve, the renal vein was cut openalong its ventral surface and the cut was continued into the common trunk formedby the union of external iliac and renal veins. The valve was easily seen protrudinginto the lumen of this common trunk (PI. 3). Apart from the presence or absence ofpapillations and slight differences in size, the fifty valves which were examinedshowed a very close similarity in their general macroscopic appearance.

Radiographic equipment and radiopaque fluid. A General Radiological ElectronicGenerator was used in conjunction with a Philips 5 in. image intensifier and a 16 mm.pulse-synchronized Arriflex camera.For still radiographs Kodak Blue Brand film was used with ultra-speed intensi-

fication screens. The exposure (with slight variation for size of bird) was 5 mAS,32 mA., 48kV. This gave an exposure time of about I sec.For cine-radiography Kodak Plus X and Kodachrome IIA 16 mm. film was used

with an exposure of 0-25 mAs, 20 mA., 48 kV. In this connexion colour film wasfound to be much better than black and white. The motor setting on the Arriflexcamera was 380, which gave a frame speed of 16/sec. Throughout both still andcine-radiography the fine focus anode (0.3 mm. diam.) was used. The radiopaquecontrast material was Micropaque. This is a finely divided suspension of bariumsulphate (particle size from 01 to I-Olt diam.) which provides an extremely goodvisualization of the blood vessels.Twenty preliminary observations were made on six different birds using Hypaque

(sodium diatrizoate) as the radiopaque fluid. This is freely miscible with blood butdoes not give as clear pictures as are obtainable with Micropaque, which has theadded advantage that it is concentrated in the liver and spleen and is not excretedby the kidneys. Thus the renal vascular field remains clear during several injectionsof radiopaque fluid. When the ventro-dorsal view of the kidney becomes obscuredby increasing liver opacity the bird is turned on its side and a lateral view providesa clear renal field again.Micropaque is diluted with water before injection (4 parts Micropaque: 1 part

water) and as it passes through the valve and renal portal veins in the same way asHypaque it was decided to use Micropaque for the main series of experiments.

Still radiography. The bird was anaesthetized as described above. After cannula-tion of the external iliac vein, using a radiopaque cannula, heparin was injected andthe bird was positioned using a binocular viewer on the image intensifier. A 20 ml.syringe full of Micropaque was then connected by a length of Polythene tubing to

366 A. R. AKESTER

Renal portal system in the domestic fowlthe venous cannula, making sure that no air bubbles entered the system. A cassettewas placed above the bird and 1-2 ml. of Micropaque (depending on the size of thebird) was injected by slow, continuous thumb pressure. Just before the end of theinjection the radiograph was exposed. A control radiograph, before any Micro-paque had been injected, was taken at the beginning of each series.When studying the flow through a single kidney, the right-hand side was found

to be more convenient because the gizzard partly obscured the left kidney whenviewed in the dorso-ventral plane. After a number of injections had been made withthe bird lying on its back, further radiographs were taken with the bird on its side.These lateral views (Pls. 8-11) were found to be very instructive when used in con-junction with the ventro-dorsal radiographs (PI. 5, figs. 1, 2; Pls. 6, 7).

Cine-radiography. Birds were prepared as for still radiography. A cine camerawas placed on the image intensifier and filming started just before the injection of1-2 ml. Micropaque into the cannulated external iliac vein. Both ventro-dorsal andlateral views were taken.

Several injections were made with an interval of 5 min. between each. After eachinjection a few drops of blood, together with any residual Micropaque, were allowedto flow out of the cannulated vein through a 'T' junction to the other side of whichwas connected the Micropaque syringe. An injection of 1 ml. physiological salineensured that no Micropaque from the previous injection remained in either cannulaor kidney so that each injection was made into a clear field.

Subsequent projection and analysis of the film made it possible to study, inconsiderable detail, the route taken by radiopaque fluid through the kidney. Theseobservations confirmed and augmented the information provided by still radio-graphy.

RESULTS

Anatomy of the renal portal systemThere is a caudal and a cranial renal portal vein in each kidney. The former is a

good deal larger than the latter and they are both branches of the external iliac vein.The external iliac vein, which is the principal vein draining the hind limb, dividesinto two approximately equal branches just before reaching the kidney. (Text-fig. 1; PI. 5, figs. 1, 2). The cranially directed branch, which is the continuation ofthe external iliac vein, anastomoses with the renal vein within the kidney to form acommon trunk. This then unites in the mid-line with its fellow from the other side toform the posterior vena cava. (Text-fig. 1; Pls. 1, 2).The caudally directed branch constitutes the caudal renal portal vein. This vein

supplies venous blood to the middle and caudal lobes of the kidney. It maintainsthe same size in its course through the kidney and anastomoses with the correspond-ing vein from the other side, in the mid-line, immediately behind the kidney. Thecranial renal portal vein branches from the external iliac vein just before the renalportal valve, and supplies venous blood to the cranial lobe of the kidney. The renalportal valve is situated within the lumen of the external iliac vein just before thisvein anastomoses with the renal vein.

There is a considerable difference between the sources of venous blood for the tworenal portal veins. The caudal renal portal vein receives many tributaries which

367

368 A. R. AKESTERbring venous blood from the hind limb, pelvis, coceyx and possibly abdominalviscera (coccygeo-mesenteric vein). The cranial renal portal vein receives blood onlyfrom the hind limb.

Outline of

Common trunkof externaliliac andrenal veins

_

Outline ofmiddle lobe

Outline ofcaudal lobe

\

Text-fig. 1. Illustrating the relationships between renal portal veins and renal veins inthe kidneys of the domestic fowl (dorsal view, cf. P1. 1).

The coccygeo-mesenteric vein is of particular interest in that it provides a directlink between the renal portal system and the hepatic portal system. It is a verylarge vein and maintains the same size throughout its length. It receives a numberof small tributaries from the hind gut in the mesentery of which it is situated.Immediately behind the kidney there is thus a three-way anastomosis of major veins;

Renal portal system in the domestic fowlthe caudal renal portal veins of each kidney anastomose with each other and alsowith the coccygeo-mesenteric vein (Text-fig. 1; Pls. 1, 2).

Variations in the route taken by radiopaque fluid through the kidney andthe activity of the renal portal valve

After injection into the external iliac vein, the route taken by radiopaque fluidas it flows through the kidney of the living bird has been shown to vary considerablyin spite of the fact that there has been no change in the external environment.Both still and cine radiographs show radiopaque fluid, on some occasions, flowing

freely through the region of the external iliac vein where the renal portal valve isknown to be (Text-fig. 2a-c; PI. 5, fig. 1; Pls. 9-11), whilst on others the vein andthe valve are outlined by Micropaque but none passes through (Text-fig. 2 d-g; P1. 5,fig. 2; Pls. 6-8). Therefore it would seem reasonable to assume that in the firstcase the valve is open and in the second case the valve is closed thus providingevidence by direct observation of the ability of the valve to open and close in theliving bird. This confirms previous deductions which have been based either onindirect evidence (Sperber, 1948) or on the activity of the isolated valve in vitro(Rennick & Gandia, 1954).About 150 radiographic observations have now been recorded (approximately

half on cine film) and, so far, only twice has the valve been seen to close from anoriginally open position. On these occasions, during a single injection (recorded oncine film in lateral view) the valve was seen to be open with radiopaque fluid passinginto the posterior vena cava; then it closed and opened, and closed and opened asecond time.These observations are thought to be particularly important as they show the

valve closing against a continuous injection pressure. The total time for thisdouble closing and opening was about 10 sec. It is also interesting to note that insome cases successive injections of radiopaque fluid into the external iliac vein ofthe same bird showed the valve to be open, then closed and then open again, illustrat-ing the fact that vascular readjustments occur independently of the externalenvironment and of the physical activity of the bird, which remained anaesthetizedthroughout. On several occasions during the same cine sequence the valve has beenobserved to open from an originally closed position. As the injection pressure wassimilar on all occasions it is suggested that the renal portal valve was not forced openby the injection but was relaxed by the physiological mechanism which normallycontrols it.When the valve was closed the most common route for radiopaque fluid to take

was by way of both cranial and caudal renal portal veins into all three lobes of thekidney (Text-fig. 2d; PI. 5, fig. 2). If slightly more radiopaque fluid was injected itentered all three lobes as before and, also, either the coccygeo-mesenteric vein (Text-fig. 2e; PI. 6) or the caudal renal portal vein of the opposite side (Text-fig. 2f) or both(Text-fig. 2g; PI. 7). On all these occasions the renal portal valve remained closedand no radiopaque fluid passed through it.On a few occasions radiographs were obtained which showed that radiopaque

fluid had entered the substance of the cranial lobe, by-passed the middle lobe andentered the caudal lobe (Pls. 6, 8). It thus appeared possible that there was some

369

A. R. AKESTER

(d)

(e)

(b) _ _

(c)

(g)Text-fig. 2. Summarizing the various routes taken by radiopaque fluid through the kidneyof an anaesthetized fowl (dorsal view). The external environment remained constantthroughout and no experimental attempt was made to influence the activity of the renalportal valve.

(a) Renal portal valve open. Fluid enters posterior vena cava, but neither cranial norcaudal renal portal vein.

(b) Renal portal valve open. Fluid enters posterior vena cava and cranial renal portalvein, but not caudal renal portal vein.

(c) Renal portal valve open. Fluid enters posterior vena cava and both cranial andcaudal renal portal veins.

(d) Renal portal valve closed. Fluid enters both cranial and caudal renal portal veins,but none enters posterior vena cava.

(e) Renal portal valve closed. Fluid enters both cranial and caudal renal portal veinsand also coccygeo-mesenteric vein, but not caudal renal portal vein of opposite side.

(f) Renal portal valve closed. Fluid enters both cranial and caudal renal portal veinsand also the caudal renal portal vein of the opposite side. It does not enter the coccygeo-mesenteric vein.

(g) Renal portal valve closed. Fluid enters both cranial and caudal renal portal veins.It also enters both the coccygeo-mesenteric vein and the caudal renal portal vein of theopposite side.

370

_ _ _-1

Renal portal system in the domestic fowldegree of vascular autonomy within each lobe and that blood entering the renalportal veins with the valve closed did not necessarily enter all the kidney lobes.When the valve was fully open, radiopaque fluid injected into the external iliac

vein passed straight through the valve into the posterior vena cava and so to theheart. There was no flow into the caudal renal portal vein and thus no radiopaquefluid entered the middle or caudal lobes of the kidney. On the other hand, with thevalve open, radiopaque fluid usually entered the cranial renal portal vein and thecranial lobe of the kidney (Text-fig. 2b).

This emphasized the difference between the source of renal portal blood for thecranial lobe, which came exclusively from the hind limb; and the source of renalportal blood for the middle and caudal lobes, which originated in the hind limb,pelvis, coccyx and possibly alimentary canal.

Occasionally, when the valve was wide open all the radiopaque fluid injected intothe external iliac vein passed directly into the posterior vena cava and neither thecranial nor the caudal renal portal vein received any (Text-fig. 2a; P1. 11). Thisrepresented the classical situation as deduced by indirect methods but was the leastcommonly occurring variant during the present series of experiments.

Several radiographs illustrated that the valve might be partly open and thatblood carrying radiopaque fluid could pass simultaneously into the posterior venacava and into both renal portal veins. On these occasions a narrow jet of opaquematerial could be seen entering the posterior vena cava through the partly closedvalve (Text-fig. 2c; PI. 5, fig. 1).With lateral radiographs the renal portal valve is sometimes shut and radiopaque

fluid can be seen to have entered both renal portal veins. The common trunk ofexternal iliac and renal veins (on the cardiac side of the valve) is not opaque but alength of radiopaque vein may be seen starting an inch or so cranio-ventral to theposition of the closed valve. This may be interpreted as the posterior vena cava, thusimplying that the valve was open an instant before taking the radiograph. It isimportant to ensure that this vessel is not the coccygeo-mesenteric vein which hasreceived radiopaque fluid from its anastomosis with the caudal renal portal vein.The alignment of these two veins (posterior vena cava and coccygeo-mesentericvein) in lateral view is rather similar.With cine radiography there is no such risk of confusion and records have been

obtained in which the renal portal valve remained closed to several injections (sothat radiopaque fluid entered both renal portal veins). After this the valve openedto allow blood to carry radiopaque fluid through to the posterior vena cava andwhilst this was continuing partial closure of the valve diverted some of the fluid, viathe caudal renal portal vein, into the coccygeo-mesenteric vein and so down to theliver. Thus the posterior vena cava and the coccygeo-mesenteric vein were radi-opaque throughout their entire lengths simultaneously and their relative positionscould easily be noted.

Other cine sequences (and several stills) illustrated the jetting of radiopaque fluidthrough the partly closed renal portal valve (P1. 5, fig. 1) and the development of aturbulent zone (cine only) of non-radiopacity immediately beyond (on the cardiacside of) the valve. This occurred at the point where blood from the renal vein joinedradiopaque fluid which had flowed through the valve.

371

372 A. R. AKESTER

DISCUSSION

The combination of radiographic techniques used in the present work provides aconvenient method for the direct observation and recording of changes that occur inthe route taken by renal portal blood as it flows through the kidney of the domesticfowl. So far only spontaneous changes have been recorded and no attempt has beenmade to influence the flow by vaso-motor drugs.

In spite of the fact that the bird was anaesthetized and lying on its back, it issuggested that the results give an accurate indication of variations in the renalportal flow in the normal animal. The same pattern of variation has been observedwith the animal lying on its back as with the animal lying on its side and it wouldseem unlikely that the position of the animal caused the renal portal valve tofunction abnormally.

In this connexion it is interesting to note that, with the bird on its back, con-tinuous direct observation of successive injections of radiopaque fluid showed renalportal blood first flowing directly to the posterior vena cava (valve fully open), thenwholly into the kidney (valve closed) and finally into both posterior vena cava andkidney (valve partly closed.) These changes occurred in a constant external environ-ment with the animal anaesthetized and therefore physically inactive. Thus it wouldseem that the suggestion by Sperber (1948) that the renal portal valve opens inorder to provide a quicker return of venous blood to meet the needs of increasedmuscle activity can only be partly correct. It is hoped that subsequent experimentalwork along lines similar to those presented here will make it possible to evaluate theeffect of body position on the renal portal flow.

It is clear that these variations are mainly due to activity of the renal portalvalve and this distinctive structure will usually be the centre of interest in anystudy of the renal portal flow through the avian kidney. The valve is situated withinthe lumen of the external iliac vein, on the cardiac side of the origin of the cranialrenal portal vein, and just peripheral to the anastomosis between the external iliacand renal veins. It is about 3 mm. long, more cylindrical than conical, and the singleaperture at its proximal end, which is frequently papillated, has a diameter ofbetween 1 and 2 mm. It is said to be the only intraluminal valve containing smoothmuscle.Some of the radiographs taken during the present work showed a good filling, with

injected Micropaque, of the cranial and caudal lobes but a relative absence of opaquefluid in the middle lobe. This was not due to a shortage of Micropaque, which, by-passing the middle lobe via the caudal renal portal vein, filled the caudal lobe andeven entered the coccygeo-mesenteric vein. Unless the middle lobe was diseased in away that upset its blood supply, it appeared as if local vasoconstriction within themiddle lobe had prevented the entrance of Micropaque.

Several radiographs showed that the renal portal valve was open and thatradiopaque fluid had flowed through it. In most of these cases the radiopaque fluidentered the cranial lobe. However, in some cases none of the fluid entered this lobe,which was thus completely by-passed by the flow from the external iliac vein.Therefore there is some evidence that a vasoconstrictor mechanism operates at thepoints where the renal portal veins enter the individual lobes of the kidney, and that

Renal portal system in the domestic fowl 373by this means each lobe controls the amount of portal blood it accepts from theportal veins. In the cranial lobe this would occur where the cranial renal portal veinleaves the external iliac vein, as its only destination is the cranial lobe. On the otherhand, in the middle and caudal lobes, this vasoconstriction would occur wherebranches leave the caudal renal portal vein to enter the kidney substance, so that itwould still be possible for portal blood to by-pass the middle and caudal lobes and toreach the liver by way of the coccygeo-mesenteric vein. However, it should beemphasized that evidence for this has only been obtained in the cranial and middlelobes and that the number of observations on this particular topic has been small.

Previous studies of the avian renal portal system have been based on the injectionof a substance into one limb and the ability to detect it in the cannulated ureter ofthe same side before it could be detected in the ureter of the opposite side. This hasbeen taken as proof that the renal portal system was functioning on the injected side(Sperber, 1948). This type of study has the disadvantage that the versatility of therenal portal system and the renal portal valve may seriously be underestimated.Indirect methods may also be misleading if it is assumed that the renal portal valveis closed when the renal portal system is functioning. Radiographic methods usedin the present study have shown that this is not necessarily the case. A furtherlimitation of indirect methods is the risk that the kidney is regarded as a singlevascular unit without the ability to make vasomotor adjustments within its variouslobes. Evidence is presented that this is not so.

Pharmacological studies have been carried out on the isolated renal portal valveof the turkey (Rennick & Gandia, 1954) in a bath of oxygenated Tyrode's solution.The results showed that acetyl-choline and histamine caused the valve to contractwhilst adrenaline caused relaxation of the histamine-contracted valve. Thus itwould seem important to carry out similar studies on the intact animal, especiallyas a rich autonomic nerve supply has recently been shown to exist in the renal portalvalve of the domestic fowl (Gilbert, 1961).An attempt to assess the renal blood flow was made by Gibbs (1928). He can-

nulated the external iliac vein (called by him femoral) and after passing the bloodthrough a flowmeter returned it to the bird via the jugular vein. He then clampedthe caudal renal portal vein ('lower clamp'), and also the common trunk of externaliliac and renal veins ('clamp 1'), and claimed that the flow of blood through theflowmeter indicated the renal blood flow. This experiment made no allowance forthe fact that the kidney received blood from two sources (arterial and renal portal).The renal portal input was partly clamped off by the 'lower clamp' but made noallowance for the fact that renal portal blood was entering by way of the other largelimb vein (sciatic in present paper), which is not shown in his diagram. Two seriousinaccuracies are to be noted in his illustration. There is no reference to the renalportal valve, activity of which would be expected to have considerable effect on theexperimentally reversed flow of blood down the external iliac vein (his femoral),and the renal vein is shown to anastomose directly with the caudal renal portal vein,which is not the case (see Text-fig. 1 for correct relationships).As for the functional significance of the renal portal system it would appear to

provide afferent venous blood to the renal tubules and so augment the arterialsupply via the glomeruli. It emphasizes the fact that tubular activity compared

with glomerular filtration in the avian kidney is probably of greater relative im-portance than it is in the mammal. The renal portal system can either bring venousblood to the whole kidney or to a part of it, presumably in amounts which varyaccording to requirements.On the other hand the coccygeo-mesenteric vein provides a large direct vascular

link between the renal portal and hepatic portal systems, and simultaneous studiesof this vein and of the external iliac vein should be very rewarding. It would seemreasonable to speculate that blood can flow along the coccygeo-mesenteric vein ineither direction and that its main function is to divert renal portal blood away fromthe kidneys to the liver, or to divert hepatic portal blood away from the liver to thekidneys, depending on the requirements of these two major organs.

SUMMARY

1. Direct observations and recordings of the renal portal flow in the domesticfowl were made by still and cine-radiographic techniques.

2. The route through the kidney taken by radiopaque fluid (Micropaque) wheninjected into the renal portal system (external iliac vein) varied considerably anddepended largely on the activity of the renal portal valve. These variations occurred,in a constant external environment, with the bird anaesthetized and thereforephysically inactive.

3. When the valve was fully open radiopaque fluid injected into the externaliliac vein passed through the valve and entered the posterior vena cava. It alsoentered the cranial lobe but not the middle or caudal lobes. Occasionally all thefluid passed through the valve and none entered the kidney tissue.

4. When the valve was closed radiopaque fluid entered all lobes of the kidneybut none passed through the valve.

5. When the valve was partly closed radiopaque fluid passed through the valveas a fine jet and also entered the three kidney lobes.

6. It is suggested that a vasoconstrictor mechanism operates at the point wherethe cranial renal portal vein leaves the external iliac vein, and where branches fromthe caudal renal portal vein enter the middle and caudal lobes of the kidney.

I wish to acknowledge the help given by Mr Ian Edgar during all the experiments,and also with the radiography and the photographic illustrations.

General Radiological (Medical) Division of the Rank Organization made a specialgrant towards the initial installation of the radiographic equipment in the Sub-Department. Their generosity also made it possible to publish the illustrations inthis paper.

REFERENCES

GIBBS, 0. S. (1928). The renal blood flow of the bird. J. Pharmacol. 34, 277-291.GILBERT, A. B. (1961). The innervation of the renal portal valve of the domestic fowl. J. Anat.,

Lond., 95, 594-598.RENNICK, B. R. & GANDIA, H. (1954). Pharmacology of smooth muscle valve in renal portal

circulation of birds. Proc. Soc. exp. Biol., N. Y., 85, 234-236.SPERBER, I. (1948). Investigations on the circulatory system of the avian kidney. Zool. Bidr.

Uppsala, 27, 429-448.

374 A. R. AKESTER

Journal of Anaetomny, Vol. 98, Pacrt 3 Plate I

|E ~ ~~ ~ ~ ~ ~ ~ ~ ~ msn i vein

~~~~~~~~~~~~~~~~~~~~~~~~~t ro ve a c

I,_~~~~~~~Ie_ j =<6 i~~~~~~~f~~ t _ , ^ in~~~~~~~Right externla

dIdle lobe E ^ 6 az

; _if let ide

_~~~~~~~~~~~~~~~~~~~~~~~e a o t,?Wall

eins~orLetai,- and ccye m sntrich

coccyxan d , D vein

A. R. AKESTER (Facing p. 374)

Journal of Anatomy, Vol. 98, Part 3

A. R. AKESTER

Plate 2

;t 7T...1

Ih :niP.-'k

Journal of Anatomy, Vol. 98, Part 3

A. R. AKESTER

Plate 3

Journal of Anatom~y, Vol. 9;8, Part 3 Plate 4

pertu~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Vt~a_S ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.14AN....... X: ''I`w[ t ? < . 1 0 0~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~E

-S. *''~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.:, , 3j@ _ . ~~~ ~ ~ ~ ~~~~~~~~~~~r :

__;~~~~~~~.......................................... .

:: ..':h .. ...... ....S~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~.........

* 1L-- L *-o'N

U.a:

*3<; -g-s A .N

.......~~~~~~~~~~~~"... .: :::t7:r

WX~~;.

MERIF~ ~ ~ ~ ~ ~ t ttit; ;~i0 0,wai': | | | S . 1~~~~~~~~~~~~~~~~~~g - _ |E || S~~~~~~~~~~~~~~~~~~~~

A. R. AKESTER

Journal of Anatomy, Vol. 98, Part 3 Plate 5

Posterior vena cava .:0.. '; t ,ds~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~. 4>.:..b:..... .... g_z.~~~~~~~~~~~~~~~~rn porta. va...... . 1

renal..pota ve _n _B

Rig h t c ran i a_1 i~~~~ight cauda

k{.~~~~~~~~~~~~~~~~~~~~e niu

ig.....3-t , R~~~~~~~~ight*.:_=_~~~~m

.~~~~~~~~~~~~~~~~

A. R. AKESTER

Journal of Anatomy, Vol. 98, Part 3

A. R. AKESTER

Plate 6

. .. .. .....

IM

Journal of Anatomy, Vol. 98, Part 3

A.:.

C

L

a-

c.) Cn Lb

C)

'U

.CE

6

tO

C1U

A. R. AKESTER

Plate 7

Journal of Anatomy, Vol. 98, Part 3

A. R. AKESTER

Plate 8

Journal of Anatomy, Vol. 98, Part 3

;;z

c

mo a

A. R. AKESTER

Plate 9

T3,

Journal of Anatomy, Vol. 98, Part 3

oa~

cC

&la-v)

a:

A. R. AKESTER

Plate 10

PJournal of Antatomty, Vol. 98, Part 3

A. R. AKESTER

Plate I11

Renal portal system in the domestic fowl 375

EXPLANATION OF PLATES

PLATE 1

Rubber latex cast showing connexions between renal portal veins and renal veins in the kidneysof the domestic fowl (dorsal view).

PLATE 2

Rubber latex cast showing connexions between renal portal veins and renal veins in the kidneysof the domestic fowl (ventral view).

PLATE 3

Renal portal valve at the junction between external iliac vein and renal vein (ventral view). Therenal vein has been cut open along its ventral surface to expose the valve. In this case there areno papillations around the valve aperture.

PLATE 4

Fig. 1. Isolated renal portal valve showing papillations around the aperture.Fig. 2. Isolated renal portal valve without papillations.

PLATE 5

Fig. 1. Radiograph (ventro-dorsal). The renal portal valve is open. Radiopaque fluid has passedthrough the valve as a fine jet to enter the posterior vena cava. It has also entered both cranial andcaudal renal portal veins and hence all lobes of the kidney (Text-fig. 2c).Fig. 2. Radiograph (ventro-dorsal). The renal portal valve is closed. Radiopaque fluid has enteredboth cranial and caudal renal portal veins and hence all lobes of the kidney. None has entered theposterior vena cava (Text-fig. 2d).

PLATE 6

Radiograph (ventro-dorsal). The renal portal valve is closed. Radiopaque fluid has enteredboth cranial and caudal renal portal veins, and also the coccygeo-mesenteric vein. Radiopaquefluid can be seen in the cranial and caudal lobes of the kidney but has by-passed the middle lobe.

PLATE 7

Radiograph (ventro-dorsal). The renal portal valve is closed. Radiopaque fluid has entered bothcranial and caudal renal portal veins, and hence all lobes of the kidney. It has also entered thecoccygeo-mesenteric vein and the caudal renal portal vein of the opposite side, but none hasentered the posterior vena cava (Text-fig. 2g).

PLATE 8

Radiograph (lateral). The renal portal valve is closed. Radiopaque fluid has entered both cranialand caudal renal portal veins. Radiopaque fluid can be seen in the cranial and caudal lobes of thekidney but has by-passed the middle lobe (cf. PI. 6).

PLATE 9

Radiograph (lateral). The renal portal valve is open. Radiopaque fluid has passed through thevalve into the posterior vena cava, which can be seen leading down to the heart in the bottomleft hand corner. Radiopaque fluid has also entered the caudal renal portal vein but has by-passedthe cranial renal portal vein (not illustrated in Text-fig. 2).

PLATE 10

Radiograph (lateral). The renal portal valve is open. Radiopaque fluid has passed throughthe valve into the posterior vena cava. It has also entered the cranial renal portal vein, but hasby-passed the caudal renal portal vein. The accumulation of radiopaque material can be seen in theliver and spleen (Text-fig. 2b).

25 Anat. 98

376 A. R. AKESTER

PLATE 11

Radiograph (lateral). The renal portal valve is open. Radiopaque fluid has passed throughthe valve into the posterior vena cava. It has by-passed both cranial and caudal renal portal veinsso that no radiopaque fluid has entered the kidney (Text-fig. 2a).

In each radiograph the bird's head is to the left. In pl. 11 a Smit Jewel focused grid (110 linesper inch) was used. The other radiographs were taken without a grid.