View source for Talk:Paper - Development of postcava and tributaries in the domestic cat (1907)

==Development of Postcava and Tributaries in the Domestic Cat==

By George S. Huntington. Columbia University, New York, and C. F. W. McClure. Princeton University.

This investigation was undertaken primarily for the purpose of satisfactorily explaining the numerous variations of the adult venous system encountered in the dissection of over 600 examples of the cat. reported in another communication by Dr. Darrach. This re-investigation of the development of the postcava and tributaries has not only entirely satisfied the original purpose, but has also made it necessary to modify the prevailing conception as to the interpretation of the postrenal segment of the adult vessel.

A bilateral and originally symmetrical venous channel develops dorsomedial to the primitive postcardinal vein by longitudinal anastomoses between somatic postcardinal tributaries. This secondary vein channel forms what we have termed the supracardinal system of veins. It extends from the level at which the posterior limb veins open into the postcardinals to a point cephalad where it joins that portion of the postcardinals which alone persists to form the anterior end of the adult Azygos. Between these levels the supracardinal veins enter into the definite organization of both the adult post-cava in its postrenal division and of the Azygos in its lumbar and part of its thoracic segments, entirely replacing in these districts the primitive postcardinal veins. The postrenal division of the adult postcava is formed as the result of a secondary median fusion by means of transverse anastomoses dorsal to the aorta of the postcaval portions of the supracardinals, the primitive postcardinal veins not entering into the formation of this portion of the main trunk of the adult vessel.

It is important to note that in our interpretation the supracardinal veins are not in any sense merely synonyms for the dorsal limb of the peri-ureteric ring described by Hochstetter and others as surmised in the discussion following the presentation of our paper, but comprise a continuous and morphologically uniform system of longitudinal vein channels contributing, as above outlined, to the establishment of the adult condition in both the post caval and in the azygos areas.



==Variations In The Postcava And Its Tributaries As Observed In 605 Examples Op The Domestic Cat==

By William Darrach. 

College of Physicians and Surgeons, Columbia University, New York.

1. Variations in the position and ureteral relation of the main postcaval trunlc.

(a) Ureter Islands. — In three cases (.5%) the cava was right-sided but double, the ureter passing between the two trunks. In one there was a short single trimk in the region of the ilio-lumbar entrance which soon divided, the two trunks again uniting well below the renal level. The right sex vein entered the more ventral of the two trunks. This corresponds to Fig. 6 of Gage. In the second case the two trunks were more distinct, the lower union being by means of a short anastomotic vessel passing from right to left, containing a small arterial island at its upper end. The two right sex veins emptied into the more ventral of the two trunks, both of which were to the right of the aorta beyond the anastomosis.

(b) Right postcava with ureter dorsal was found in 22 cases (3.6%). This condition differed from the normal only in that the ureter passed at first dorsad of the cava, then mesad and ventrad, again crossing ventrad of the common iliac vein to reach the bladder. This condition would obtain if the dorsal of the two trunks in the island formation were omitted.

(c) A left postcava with the ureter ventral was found in 21 cases (3.4%). Here the cava, after its formation by the union of the two common iliacs, as normally, passed cephalad lying to the left of the aorta, receiving the left sex vein. The right sex vein in 13 cases opened into the renal and in the remaining 8 cases into the cava.

(d) A left postcava, the ureter lying dorsal was found in 7 cases ( 1.15% ) . This variety was similar to type c, except that the ureter passed dorsad of the cava. In four of these the right sex vein entered the cava as well as the left. In the other three it emptied into the right renal, and in two of these it was associated with a spinal or somatic branch.

(e) A double postcava, both ureters being dorsal, was found in 20 cases (3.3%). In 14 cases there were two separate trunks which continued the common iliac trunks on cephalad to the renal region without anastomosis. In the remaining six the two trunks were connected by cross anastomoses, sometimes double and once triple. In two of the cases the two trunks were asymmetrical, the right being the larger. The point of fusion of the two cavae varied, being either above, at, or below the right renal entrance, but always above the left renal level.

(f) A double postcava, one ureter being ventral and the other dorsal, was found in three cases. In one the ureter was dorsal to the left cava and ventral to the right with no cross anastomosis. In the second the same ureteral relation existed, but there was a large vessel connecting the left common iliac with the right trunk and containing an arterial island. In the third case the condition was reversed, the ureter being dorsal on the right side and ventral on the left. The two trunks were asymmetrical here also, the right being the larger of the two.

(g) A double postcava with both ureters ventral was found partially represented in one case where, after a rather high fusion of the common iliacs, the cava again split into two unequal trunks, both of which were free of the ureters. There was a large cross anastomosis at the level of the inferior mesenteric artery and the caudal veins entered at different levels into the two trunks.

2. Variations in the sex veins.

Out of the 100 variants both sex veins entered the cava in 12 cases, all being in left cavae, 8 with the ureters normal and 4 dorsal.

In 14 cases the sex veins were multiple. In two cases bilateral and in two triple.

A vein draining the region caudad of the kidney (called capsular) emptying into the sex vein is almost constant. A cross anastomosis betv:een the two sex veins was present in two cases out of 286. In the same number a communication was found between the sex vein and the iliolumbar vein. A ureteric vein was very frequently found entering the sex vein. Occasionally the latter is associated with a somatic vein near its entrance.

3. Island formation.

Besides the ureter islands already mentioned, islands were found in the regions of the ilio-lumbar entrance, common iliacs, iliac fusion and in the "main caval trunk. Tlie common iliac islands may transmit the whole internal iliac artery or only its dorsal branch, either with or without the obturator nerve. It may be unilateral or bilateral. Islands in the region of the iliac fusion are quite complicated, depending on cross anastomoses at different levels, and either dorsal or ventral to the caudal and internal iliac arteries. In two cases a small island was found in the main caval trunk transmitting a small somatic artery. The frequency of occurrence of these islands is shown in tlie following table:

Ureter Islands 5% in 605 cases.

Iliac Fusion 4.0% " 375

Common Iliac 4.0% " 375 "

Ilio-lumbar 2.7% " 375

Caval 53%

4. Variations in arterial relations.

In two cases out of 286 the sex artery passed cephalad of the left renal vein. In three cases out of T8 the right sex artery was dorsal to the Cava. In one case out of 605 the ilio-lumbar vessels on both sides passed dorsal to the psoas minor muscle, corresponding to the Marsupial condition. In one case out of 605 tlie left ilio-lumbar artery passed dorsal to the left caval trunk. In three cases out of 605 a spinal artery passed ventral to a eaval trunk. In two cases out of GOo the right renal artery was given off at the level of the inferior mesenteric artery and passed cephalad and dorsal of the Cava. In one case out of G05 the ri^rht renal artery passed ventrad of the Cava 1.4 cm. caudad of the right renal vein.



==The Interpretation Of Variations Of The Postcava And Tributaries Of The Adult Cat, Based On Their Development==

By George S. Huntington. Columbia University, yeic York, and C. F. W. McClube. Princeton University.

The explanation of the adult variations encountered in an extensive series of adult examples of Felis domestica is fully afforded by the comprehensive system of embryonal vein channels normally and functionally present during certain ontogenetic stages in the cat. The acquisition of what is regarded as the normal type of adult postcava in this animal depends on the selection and continued development in the majority of individuals of certain of these embr3-onic pathways, the remainder undergoing degeneration and affording, as will be shown in a subsequent communication, the possibility for the correlated development of the main adult lymphatic channels. The average individual thus assumes the venous and lymphatic type considered normal for the species. In the case of individuals variant in the structure of the adult postcaval system, any one or several of the temporary early venous pathways, present normally in typical consecutive embryonic stages, may abnormally persist and by continued development give rise to the relatively enormous series of graded adult variants observed in the series of 600 dissections reported by Dr. Darrach. The details of this process of atypical selection of embryonal channels normally destined to become obliterated during the development of the adult venous type, are so closely dependent upon the ontogenetic changes involved that the full consideration of this topic is deferred to a subsequent publication, fully illustrated by typical sections and reconstructions. It has, however, been possible for us, by means of the large series of cat embryos examined and reconstructed, to produce a composite reconstruction of all the possible and available venous pathways of the embryo, and to thereby interpret all of the observed adult variants as examples of atypical persistence of early channels normally destined to disappear in course of further development, but capable, by continued and unusual growth, of affording all of the variations of the adult venous system observed in the cat. These observations also make it extremely probable that in the case of corresponding variations in the adult human subject we are dealing with developmental factors of exactly identical force and influence.