Paper - development of the postcaval vein in birds (1903)

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Miller AM. development of the postcaval vein in birds. (1903) Amer. J Anat. 3: 283-299.

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This historic 1903 paper by Miller



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The Development of the Postcaval Vein in Birds

By

A. M. Miller.

Class-of-77-Fellow-in-Biology, Princeton University.

With 10 Text Figures.

  • Presented to the faculty of Princeton University for the degree of Ph. D.


This subject was suggested to me by Professor C. F. W. McClure, under whose direction the investigation has been carried on. Professor McClure has shown the greatest kindness and interest during the time of my research in his laboratory, for which I am deeply grateful; and I take unusual pleasure in acknowledging my indebtedness to him for the most valuable assistance throughout my work.


The development of the postcaval vein seems to have been much less investigated in birds than in the higher and lower forms, Hochstetter's articles being the only ones known to the writer as relating to this subject. In reptiles and mammals, on the other hand, the development of the postcava has been worked out in several different orders by a number of investigators. Hochstetter's (88, 93) observations on the chick are very accurate as recorded in his brief general description; a detailed account, however, is lacking. It will be the purpose of the writer in the following pages : ( 1 ) To corroborate Hochstetter's general observations on the development of the postcava in the chick; (2) to compare the mode of development in the chick with that in another form, viz. : the English sparrow; (3) to show that a portion of the efferent vessels of the primitive kidney {Yv. subcardinales) persists in birds as a part of the postcava in the adult, as Lewis (02) has recently shown to be the case in mammals.

The writer has reconstructed the venous system in a complete series of English sparrow {Passer domesticus) embryos, and also in series of chicks (Gallus galhis). The veins in the liver region have been reconstructed in wax. The burden of the work is based on the sparrow, but numerous comparisons have been made M'ith the chick and the modes of development in the two forms found to be so very sim.ilar, differing in only a few unessential points, that figures taken from both are used for illustration. The accompanying figures (except Figs. 1 and 8) represent actual reconstructions and are not in any sense diagrammatic. The suhcardinal system tliroiighout the series of illustrations is marked with crosses in order to facilitate the tracing of that portion of the postcava through the successive stages of development up to the adult condition. The suhcardinal veins in the sparrow and chick are first found as a series of unconnected vessels or islands situated on each side hetween the

mesonephros and the aorta (Fig. 1,V. sc. dands). This is at a very early stage, between the 60th and 70th hour in the chick, when the germ-layers are still flat except in the head region. In Fig. 2 (V. sc. d. and s.), the above mentioned islands are shown; on the right is seen a communication between the postcardinal and subcardinal. These islands subsequently fuse to form con -FiG. 1. Cross-section of a verv von njr sparrow embryo. correspondine: to a chick 60-'70 hours: taken at tinUOUS VCSSCls m whlch the tbe level of the A. omphalomesenterica. The asterisk (*) in Figr. 2 indicates the level of the above section, bilateral SVmmetrv IS Complete. This tusion, however, may not be accomplished until after the proximal part of the postcava is developed.

The development of the subcardinals seems to correspond to the development of the mesonephros: as the mesonephros becomes larger the veins increase in length and calibre, and in the earlier stages they are found to extend the full length of this organ. A number of direct communications between the postcardinal and subcardinal veins are present, which pass between the mesonephros and the aorta. In Fig. 4 (sparrow, corresponding to a chick of 90 hours) three of these communications are seen on each side. So long as the mesonephros is small these anastomoses are of considerable size and importance, but as this organ develops they are broken up in the mesonephric circulation, and cease to exist as well-defined vessels. However, the subcardinals may remain in communication, at their anterior ends, with the postcardinals even after the postcava appears (Figs. 4 and 5). In the chick the writer has observed other direct connections between the subcardinals and postcardinals in the form of welldefined vessels enclosed within the ventral part of the mesonephros. These vessels are shown in Fig. 5 (b) (chick, 90 hours) lying at the side of the subcardinals and ventral to the postcardinals. No particular importance is to be attached to them since they, like the other anastomoses between the postcardinals and

the circulation through the mesonephros. Soon after their first appearance the subcardinals receive blood from the mesonephros through a number of small branches which enlarge as the above organ enlarges. In the figures of the early stages these branches have been omitted to avoid confusion.


2 Lettering of all Text Figures. — In the abbreviations d and s always refer to dextra and sinistra respectively.

n. (Fig. 6), mesonephric veins. A. i. id and s), A. iliaca. Ao., aorta. ^1. o. m., A. omphalomesenterica. A. sc. id and s), A. sciatica. A. u. (d and s), A. umbilicalis. b. (Fig. 5), vessels enclosed within ventral side of mesonephros. c, cranial portion of the right suhcardinal vein. d. (Fig. 7), anastomosis between posterior ends of postcardinals. D. C. {d and s), ductus Cuvieri. D. V., ductus venosus. ki. (Fig. 8), kidney, m., mesonephros. .s. g. (Fig. 8), sexual gland. Ur., ureter. V. c. (Fig. 7), V. coccygomesenterica. V. c. i., V. cava inferior (V. postcava). V. c. i. H. (Fig. 7), V. postcava, pars hepatica. V. c. i. SC. (Fig. 7), V. postcava, pars subcardinalis. V. c. p. (d and s), V. cardinalis posterior. V. c. p. id and s) {V. i. i.), V. cardinalis posterior (V. iliaca interna.) Vi'. g., Vv. genitaliae. V. h. r., V. hepatica revehens. V. I. c. d. (Fig. 9), V. iliaca communis. V. i. e. (d and s), V. iliaca externa. V. i. I. {d and .s), V. interverte.bralis lurabalis. V. r. in. (d and s), V. renalis magna. V. .s-. .s., V. sciatica. V. sc. (d and s), V. subcardinalis. Vv. sr. s., Vv. suprarenales, T^ u. id and s), V. umbilicalis. W. d., Wolffian duct. x. (Fig. 10), dorsal portion of loop around umbilical artery.


subcardinals mentioned above, Reconstruction .itthevenous system

' of a very youiitr siianow embryo, correspond are subsequently broken up in !"?r*°,%!.?/), ,V- '"' ;'! \\^'"- ^'entrai view.

X *5. {Explanatinn iifletterDni 0)1 page 2Si.)


In his article on the development of the postcaval vein in mammal;:; Lewis (02) has attempted to explain the presence of the subcardinals on the ground that the course of the blood through the postcardinals is impeded by the mesonephric tubules and the recurrent bend of the duct of Cuvier, and hence these vessels are the result of an attempt of the postcardinals to disentangle themselves from the mesonephros. He has apparently overlooked the fact that the subcarclinal veins have their ancestors, so to speak, in similar structures in birds and reptiles, which have been described by Hochstetter and others under the name of the eiferent veins of the* primitive kidney, and consequently have not been called into existence in mammals by any physiological reason. Furthermore, Lewis states that the subcardinals are tributaries of the postcardinals, formed from certain branches of the latter veins which pass ventrad between the mesonephros and the aorta. However this may be in mammals, it is certainly not the case in the chick or sparrow. As has been stated earlier in this article, the subcardinals arise as unconnected vessels or islands, which are without a doubt independent structures; and the connections with the postcardinals are formed later and secondarily.

It is a noteworthy fact that in birds, at least, the subcardinal veins ajjpear and attain a considerable size before the postcava begins to develop. This is plainly seen in Figs. 4 and 5, where the postcava (V. c. i.) is in its incipient stage, and in Fig. -i is composed of merely a few islands situated in the anlage of the liver and the caval mesentery.

The writer has carefully reconstructed in wax the veins in the liver region and has found almost a perfect agreement with Hochstetter's description and illustrations. However, to clear up some slight doubt in regard to the exact point where the postcava joins the ductus venosus, it has been thought best to insert a figure and brief description of the conditions found in the sparrow at a very early stage of development (Fig. 3, sparrow corresponding to a chick of 90 hours). As shown in this figure the right and left omphalomesenteric veins fuse at a very early stage to form the ductus venosus (D. V.). The sinus venosus (S. Y.), Avhich is virtually a continuation of the ductus venosus, is formed by a union of the latter vessel and the two ducts of Cuvier (D. C. d and s), and empties into the right auricle of the heart. The right and left umbilical veins (V. u. d and s) join the right and left ducts of Cuvier respectively some distance from the opening of the latter vessels into the sinus venosus. The postcaval vein (Y. c. i.) at this -stage has not joined the ductus venosus. But its point of connection, as shown by a closely succeeding stage, is found to be on the dorsal side of the ductus venosus just caudal to the union of the latter vessel Avith the ducts of Cuvier (indicated by an asterisk in Fig. 3).

A marked dilference is seen here between the relations of the proximal end of the postcava in reptiles, birds and mammals. While in birds it arises as a branch of the ductus venosus (Hochstetter, 88, 93), in reptiles it arises either as a bran(3h of the right


Fig. 3. Drawn from a wax reconstruction of the veins

ompnaiomesenteric vem in the liver region of a sparrow embryo ; taken from the

/T . \ -1 QTinVi same specimen as Fig. 4. Outline of liver dotted. Dorsal

^^Ijacertaj or as a Orancn view, x about t^. (t:.rpJanation of lettering on i>cg>'~^i-^

of the union of the latter

vein with the right umbilical (Tropidonotus) ( Hochstetter, 92). In Echidna (Hochstetter, 96) the right V. hepatica revehens forms the common stem of the postcava and the ductus venosus Aranzii. In the higher mammals thus far observed it arises from the V. hepatica revehens communis (Hochstetter, 93, Lewis, 02).

The postcaval vein in the chick first appears about the 90th hour of incubation, as Hochstetter has observed, though the writer has noticed it in the initial stages somewhat earlier. The liver at this time is composed of merely a few tubules surrounding the ductus venosus. Among the tubules are to be seen a number of small venous islands, or hepatic sinusoids, as Minot has called them. The hepatic portion of the postcava is the result of a fusion of some of these sinusoids lying dorsal to the ductus venosus, that is, in the dorsal part of the right lobe of the liver. At this stage there is also found a series of venous islands extending through the eaval mesentery, and ending on the median side of the right mesonephros a short distance anterior to the origin of the A. omphalomesenterica. These islands are in the direct line of the future continuous postcaval vein, and by their fusion, which takes place soon after their first appearance, the portion of the ])ostcava between the liver and the mesonephros is formed.

In his description of the development of the postcava in the chick Hochstetter (88, 93) does not state the fact that it is derived through a fusion of islands in the caval mesentery and through the fusion of a number of hepatic sinusoids. In his work on the mammals, however, he indicates that the postcava arises in some such manner (" durch Erweiterung iiiul Zusannnentliessen schon vorhandener Vencnbahnen/' 93, p. 5G8). Thus it appears that the early formation of the hepatic portion of the postcava takes phice (ni the same principle in both birds and mammals.

The above mentioned islands of the postcava are shown in Fig. 4 (V. c. i.). The anterior island is of sinusoidal origin; the others are situated in the caval mesentery, extending from the liver in front to the median side of the right mesonephros some distance anterior to the origin of the A. omphalomesenterica. At this stage the islands of the subcardinals have not yet undergone a complete longitudinal anastomosis. In Fig. o, which represents a slightly older stage than Fig. 4, the subcardinal on each side is a continuous vessel extending from a point just caudal to the duct of Cuvier almost to the level of the umbilical arteries — in other words the full length of the mesonephros. At their anterior ends both subcardinals join the postcardinals; all other direct connections between the former and latter veins have been broken up in the mesonephric circulation, Avith the exception of the vessels described above as situated in the ventral part of the mesonephros (Fig. 5, b). Here the islands of the postcaval vein have also fused to form a continuous vessel c. i.), Avhich, however, has not yet joined the ductus venosus, ends in the hepatic sinusoids. This latter condition is short lived, for in an embryo but slightly older than that represented in ¥ig. 5 the postcava joins the ductus venosus. The postcava after it makes its exit from the caval mesentery joins the right snbcardinal some distance in front of the origin of the A. omphalomesenterica. Thus the posterior portion of the right snbcardinal becomes the direct continuation of the postcava, and a renal portal system is established on the right side. Soon after this, however, an anastomosis takes place between the two subcardinals ventral to the aorta and caudal to the A. omphalomesenterica, and by this means the blood from the left subcardinal also passes into the postcava. This brings about a complete renal portal system. The anastomosis between the two subcardinals marks the future bifurcation of the adult postcava. As the mesonephroi enlarge and occupy a considerable portion of the body cavity they grow around the subcardinals, wliicli thus become enclosed within their median side and are carried somewhat ventrad. This brings about a closer relation between the mesonephroi and the subcardinal veins. In consequence of this closer relation the latter vessels increase in size and receive blood from the mesonephroi through large branches, as indicated in Fig. 6 (a) (chick of 5 days' incubation) With the increased amount of blood from the mesonephroi and the enlargement of the snbcardinal veins the stem of the postcava attains corresponding i)ro|)ortions. At the end of tlic r)th day of incubation the snbcardinal system has reached its lieight of development, and at this stage is seen the immense importance of the snbcardinal veins in the development of the postcava. They form the entire efferent system, and moreover a great quantity of blood passes through the renal portal system, for the anterior ends of the postcardinals by this time have become much diminished in size and are unable to carry a very large proportion of the blood to the duct of Cuvier.



Fio. 4. Keconstructiini of the venous system of a sparrow embryo, corresponding' to a chick of about 90 hours. Ventral view. X 75. {Explanation of lettering on page 284.)



Fig. 5. Reconstruction of the venous system of a chick of 90 hours. Ventral view. X 50. {Explanation of lettering on page 284.)



The significance of these snbcardinal veins in birds is even better appreciated by a glance at the conditions found in adult reptiles, where the efferent veins of the renal portal system persist in part as paired vessels which connect anteriorly with the unpaired portion of the postcava (Hochstetter, 93). The efferent vessels in birds are undoubtedly the homologues of the paired portion of the postcava in reptiles. In mammals also Hochstetter (93, 96) has described a pair of vessels running on the median side of the mesonephros, which unite with the stem of the postcava; McClure has observed the same conditions in Didelphys and LcAvis (02) has described these vessels in the rabbit under the name of the snbcardinal veins. The sub cardinals in birds are certainly homologous with the vessels in mammals described by the above investigators, even though a true renal portal system is not established in the higher mammals. Hochstetter has already mentioned the homology of the snbcardinal veins, running through the three classes of animals ]nentioned above, but it has not been brought out with sufficient emphasis.

Fig. 6 (chick of 5 days' incubation) shows the large above-mentioned anastomosis between the two subcardinals caudal to the A. omphalomesenterica. Note the great relative size of the snbcardinal veins and the branches (a) from the mesonephroi emptying into them; there are also many smaller branches which have been omitted in the reconstruction. The anterior ends of the postcardinals are seen to be considerably diminished in size. The stem of the postcava has become a relatively large vessel, for it now carries a great quantity of blood to the heart.

The snbcardinal veins have been indicated by crosses throughout the series of illustrations; and a comparison of Figs. 2, 4, 5 and 6 will enable one to trace clearly the progressive development of the snbcardinal system up to its height at the end of the 5th day of incubation in the chick, and furthermore will enable one to appreciate the vast importance of the snbcardinal system in the earlier stages of development.


At about the stage from which Fig. 6 was taken (5th day of incubation) the Avriter found a most interesting exception to the general plan of development of the siib-r cardinal system in birds, c. Vscd.

which exception shows a striking combination of the conditions described by Hochstetter in reptiles and Echidna. Anterior to the origin of the A. omphalomesenterica and ventral to the aorta there is present a large anastomosis between the right and left subcardinals, just caudal to the point where Vc.p.d the postcava joins the right subcardinal. Such a remarkable similarity to the conditions found in the earlier stages of reptilian development is certainly unusual. Then in addition to the usual anastomosis between the two subcardinals caudal to the A. omphalomesenterica there is also another large anastomosis about midway between the A. omphalomesenterica and the A. iliaca, which re ininrlc nno I'orv iTmr-li r,f +Vi D FiG. 6. Reconstruction Of the veiious System of a mmciS one \ery mucn 01 tne chick of 5 days. Ventralview. X3V. (Explanalion State of affairs in Echidna, of lettering on page 2Si.)

though the fusion takes place to a less degree than in the latter. Having found only this one example in all the specimens examined it would be going too far to assert that the above 'conditions in the chick are more than accidental, despite the fact that they exhibit such a striking resemblance to reptiles and Echidna.

After the 5th day of incubation the subcardinals begin to decrease in importance, for with the gradual atrophy of the mesonephroi they have less and less of the function of efferent vessels to perform. The portion of each vessel caudal to the anastomosis becomes shorter; the anterior end of the left vein diminishes while the corresponding part of the right disappears entirely.



During the process of development tlie right lobe of the liver enlarges and grows backward, and thus includes the portion of the postcava which was at first situated in the caval mesentery and which is designated in Fig. 7 as pars liepatica (V. c. i. H.).



Fig. 7. Reconstruction of the venous system of a sparrow embryo, corresponding to a chick of about 14 days. Ventral view. X 30. {Explanution of lettering on pai/e 284.)

In Fig. 7 (sparrow, corresponding to a chick of 14 days' incubation) the subcardinal portion of the postcava (V. c. i. SC.) is seen to be relatively small, the mesonephros having diminished to an unimportant organ on each side. Practically all that now remains of the subcardinal system is the previously described anastomosis caudal to the A. omphalomesenterica. From this time on the subcardinal portion of the postcava diminishes in size still more as it approaches the adult stage. In the adult the subcardinal system has diminished to a small part of the postcava just proximal to the bifurcation, including the area into which the genital and suprarenal veins open.

Our attention will now be directed to the development of the genital and suprarenal veins which have been mentioned in the above pa:ragraph. About the 5th day of incubation in the chick the suprarenal bodies are found lying between the aorta and the mesonephros on each side, dorsal to the subcardinal vein and anterior to the large anastomosis. Soon after this t^ie sexual glands appear as elongated bodies situated on the median wall of the mesonephros and medial or ventral to the subcardinals. Both sets of organs give blood to the subcardinals.

As has been mentioned before, the portion of the right subcardinal vein cranial to the point where the postcava joins the former vessel (cranial portion of the right subcardinal, marked c in Figs. 5 and 6) atrophies (Fig. 6) and finally disappears (Fig. 7), So far as the writer has been able to determine, the suprarenal body of the right side does not at any period of development give branches to the cranial portion of the subcardinal. In Fig. 7 (sparrow, corresponding to a chick of 14 days' incubation) the subcardinal portion of the postcava itself lies embedded in the ventral side of the suprarenal body and receives branches coming directly from the organ. Thus the right suprarenal vein is really a subcardinal derivative, inasmuch as the stem of the postcava is of subcardinal origin, but it is not a subcardinal derivative in the same sense as the left suprarenal and genital veins.

On the left side, on the other hand, the suprarenal veins are, from the beginning, branches of the anterior end of the subcardinal; and as the anterior end of the left mesonephros gradually disappears the corresponding portion of the subcardinal becomes smaller, and finally in the adult stage the suprarenal veins of the same side form the only portion that persists, and these open into the pars subcardinalis of the postcava. In Fig. 7 the suprarenal veins (Vv. sr. s) are seen as branches of the anterior end of the left subcardinal vein, and in Fig. 9 (adult) as branches of the subcardinal portion of the postcava. The development of the suprarenal veins in birds, as described above, seems to agree with the conditions found in mammals as described by Hochfitetter.

As has been stated, the sexual glands are at first elongated bodies.


While the glands are in tlieir earlier stages of development they may give blood to the subcardinals through several small branches. As theglands become shorter, approaching the adult condition, some of thesesmall branches disappear, and finally one or two remain on each sidewhich ultimately persist as the spermatic or ovarian veins emptying into the pars subcardinalis of the postcava just cranial to the bifurcation. In Fig. 7 the genital veins (Vv. g.) are seen as branches of thesmall remaining part of the posterior ends of the subcardinals.

Hochstetter (88, 93) advanced the idea that the spermatic or ovarian veins in birds were formed from the subcardinals (efferent veins of theprimitive kidney), though he did not make a positive statement and gave no illustrations. There certainly can he no doubt that the genital and at least tJie left suprarenal veins are derived directly from the subcardinals.



Fig. 8. Outline sketch of a crofes-sectioii tliroug-h a sparrow embryo,, corresponding- to a chielv of 14 days; taken a short distance caudal to thebifurcation of the postcava. Showing relative position of the great renal. veins. X about 20. {Expla.mifioii of Icttcriiifi 011 puye 284.)


Fig. 8 shows the adult conditions in the postcaval vein. It is rather difficult to state with certainty to just what extent the subcardinal system persists. The writer has carefully considered the matter and has indicated by crosses a small portion proximal to the bifurcation into which empty the suprarenal (V. sr. s) and the spermatic veins (Vv. g.). It may be safely stated, however, that the subcardinal system persists at least as a small portion of the postcava proximal to the bifurcation,, which portion, as stated above, is marked by crosses. Furthermore the genital and left suprarenal veins are true subcardinal derivatives and' empty into the subcardinal portion of the postcava.



In Fig. 7 a pair of important vessels are shown which have not been present in the preceding illustrations. These are the Vv. renales magnae (V. r. m. d and s), the efferent veins of the permanent kidney. There are also Iavo other smaller vessels which appear for the first time in this figure — the Yv. intervertebrales lumbales (V. i. 1. d and s).

Before the pennanent kidney appears the anterior ends of the postcardinal veins have atrophied and disappeared. The kidney begins to develop about the 6th day of incubation and is situated dorsal to the mesonephros and lateral to the aorta and chorda. As soon as the head end develops the V, intervertebralis lumbalis appears as a small vein enclosed among the tubules, which empties into the postcardinal at the same level as the external iliac vein. As the head end of the kidney enlarges this vessel becomes larger and in Fig. 7 (V. i. 1. d and s) is seen to be a vein of considerable importance. Moreover, the segmental (vertebral) veins which previously emptied into the enterior end of the postcardinal now open into this new vessel. It functions as the efferent vein of the head end of the kidney (Fig. 9, Y. i. 1. s.).

After the kidney has attained a considerable size still another vessel, the Y. renalis magna, is developed on each side as a branch of the subcardinal system at the level of the large anastomosis; but it is not included in tne subcardinal system. This vein runs laterad from the anastomosis till it reaches the dorsal side of the mesonephros, that is, it reaches a position on the median side of the kidney. As the kidney develops the above vein becomes more or less enclosed within its ventral side (Fig. 8) and growing caudad, finally extends to the level of the umbilical artery. "While the mesonephros persists it receives a small amount of blood from this organ; but its more important function is to carry blood from the kidney to the postcaval it is the large efferent vein of the kidney. When the great renal veins have reached an advanced stage of development, as in Fig. 7, they anastomose with the postcardinals at the level of the external iliac veins. They approach h-o near the postcardinals that the walls break through and tliere then exists a direct channel on each side from the postcardinal to the postcava. Thus the renal portal system is destroyed. It is interesting to note, as Hochstetter has done, that a renal portal system of the permanent kidney also exists before the anastomosis between the great renal veins and the postcardinals; for more or less blood is given to the kidneys by the postcardinals which in turn is carried to the postcava by the great renal veins. But as soon as the above anastomosis takes place this renal portal system is destroyed, as well as that in the mesonephroi.




Fig. 9. Region of the bifurcation of the postcava in the adult domestic fowl, showingthe part of the postcava which is formed from the subcardinal system, and the relations of the common iliac and great renal veins The right V. intervertebralis lumbalis is omitted and instead the small efferent renal veins are shown. Ventral view. Natural size. {Explanation of leLteriny on page 284.)



In Fig. 7, on the right side, the anastomoeis between the great renal vein and the postcardinal is shown ; the one on the left has not 3^et taken place. As a general rule they occur about the 14th or 15th day of incubation in the chick and at a corresponding stage of development in the sparrow. After these anastomoses the adult condition is practically reached and it only remains for a few changes in relative position to take place. In Fig. 7 the anastomosis is seen to be very short; but during further development it lengthens out to a consideral)le extent so that in the adult condition it forms about the distal half of the common iliac vein. What was originally the proximal end of the great renal vein forms the proximal half of the common iliac vein. (Compare Fig. 9).

There remain to be described two important changes which take place in the region of the posterior portion of the postcardinal vpins: (1) About the 6th day of incubation in the chick an anastomosis between the two postcardinals is found far back in the tail-region, which lies ventral to the caudal aorta. As the tail-region shortens up in the process of development the anastomosis is gradually pushed forward till it reaches the normal position just caudal to the posterior lobe of the kidney about the 11th day. In the meantime the V. coccygomesenterica has developed and on the 8th day it is seen as a small vessel coming from the dorsal surface of the hind gut. It joins either the anastomosis directly or the one or the other postcardinal anterior to the anastomosis; l)ut in the latter case it finally joins the anastomosis itself. In the adult it communicates directly with the hepatic portal system (vide Fig. 7, d, V. c).

(2) The other change takes place in the postcardinal veins in relation to the umbilical arteries. In the early stages of development the postcardinals are found lying ventral to the umbilical arteries (Figs. 4 and 5), which condition is characteristic in reptiles. About the 5th day of incubation in the chick, and at a corresponding stage of development in the sparrow, a new venous channel is found dorsal to the uinltilical artery, which seems to be a sort of anastomosis between the proximal ends of the TuigJiborin g verteliral veins (Fig. 10, x, sparrow, corresponding to a chick at the end of the 5th day). This dorsal channel increases rapidly in size and by the following day is as large as the ventral channel. The latter channel decreases and, as a general rule, disappears about the 7th day, thus leaving the postcardinal vein on the dorsal side of the umbilical artery. (Compare Figs. 4, 5, 6, 10 and 7.)




Fig. 10. Reconstruction from a sparrow embryo, correspondinsr to a chick of 5 days. Showing venous k)op around the umbilical artery. Left side. X 75. {Explanation of letter'infi on page 384.)



These observations were also made by Hochstetter (93) in the chick. In his article on the reptiles (93, p. 495) he explains the formation of the loop around the umbilical artery in birds on a mechanical basis by saying that the large umbilical artery (in birds) exerts a pressure on the dorsal side of the neighboring portion of the postcardinal vein, which bends the vein downward. The blood then seeks a more direct course which results in the formation of a collateral channel dorsal to the artery, while the ventral portion of the loop then disappears.

There is a possibility that Hochstetter's explanation would suffice in some instances in birds where the loop is very short; but the writer has found cases where the loop is very much extended antero-posteriorly ; in one case, indeed, it extended almost from the level of the external iliacveins to the anastomosis, described above, caudal to the posterior lobeof the kidney. Furthermore, McClure (00, 02) has described variations in Didelphys where the veins may be dorsal to the artery, or ventral to the artery, or both dorsal and ventral to the artery; and certainly no mechanical principle is adequate to account for such extreme variations, where a similar loop formation is present in the embryo. It seems to the writer that the explanation of the formation of the loop around the umbilical artery is to be sought in some underlying physiological principle,

Resume

Up to the end of the 5th day of incubation the subcardinal system increases in size and importance; from the 5th day on it decreases up to the adult stage, where it persists only as a small portion of the stem, of the postcava and the genital and suprarenal veins.


The following table shows a comparison of the development of the stem of the postcava in birds with that described by Lewis in mammals :

Rabbit. Birds.

_^ , . , . (Sinus venosus.

V . hepatica revehcns commnnis . . . <^ -^^ • ^ i £ ^ i.

Proximal end ot dnetus venosus.

Hepatic sinusoids J '^^'P^^^^^ sinusoids.

j Independent islands in caval mesentery.

, ... ( Jvight subcardinal and anastomosis

TJight subcardinal •{ ,, .,, ji^x i, v ^

^ I between right and left subcardinal.

Caudal to the bifurcation of the postcava in birds it is difficult to draw a comparison between birds and mammals. The so-called common iliac vein in birds is an independent formation, the proximal end being the original proximal end of the great renal vein; the distal end of the common iliac is formed by an elongation of the anastomosis between the great renal vein and the postcardinal. The external iliac vein in birds is also an independent structure, and the internal iliac i«  the posterior portion of the original postcardinal.

Literatuke Cited

HocHSTETTER, ¥. — Beitriige 7Air Entwickelnngsgeschichte des Venensystems der Amnioten. I. Hlihrichen. Morph. Jahrb., B.' XIII, 188S. p. 575.

Entwickelung des Venensystems der Wirbeltiere. Ergeb. d. Anat.

u. Entwick., B. Ill, 1893, p. 460.

Beitrag-e znr Entwickelnngsgeschichte des Venensj'stems der Am nioten. II. Reptilien. Morph. Jahrb., B. XIX, 1893, p. 428. — Beitriige zur Entwickelnngsgeschichte des Venensystems der Amnioten. III. Sanger. ]\rori3h. Jahrb., B. XX, 1893, p. 543.

Beitriige zur Anat. u. Entwick. des Blutgefasssystems der Mono tremen. Jena Denkschrift, B. V, 1896, p. 189.

— Znr Entwickelung der Vv. spermaticae. Anat. Hefte, B. VIII, H. IV,

1897, p. 802.

Ueber den Einfluss der Entwickelung der bleibenden Nieren auf die

Lag'e des Urnierenabschnittes der hinteren cardinalen Venen. Anat.

Anz., B. Ill, 1888, p. 938. — Ueber das Gekrose der hintei-en Hohlvene. Anat. Anz., B. Ill, 1888,

p. 965. Lewis, F. T. — Development of the V. cava inferior. Am. Jour, of Anat.,

Vol. I, No. 3, 1902, p. 229. McClure, C. F. W. — Variations of the Venous System in Didelphys vir giniana. Anat. Anz., B. XVIII, 1900, p. 441.

Development of the Postcaval Vein in Didelphys virginiana. Science,

N. S. Vol. XV, No. 379, 1902, p. 529. MiNOT, C. S.— Veins of the Wolffian Body in the Pig. Proc. of Boston Soc. of Nat. Hist., Vol. XXVIII, No. 10, p. 265.


Cite this page: Hill, M.A. (2020, September 28) Embryology Paper - development of the postcaval vein in birds (1903). Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_development_of_the_postcaval_vein_in_birds_(1903)

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