Talk:Paper - Some abnormal developments in the vascular system of the frog (rana temporaria) (1915)

SOME ABNORMAL DEVELOPMENTS IN THE VASCULAR SYSTEM OF THE FROG (RANA TEMPORARIA). By Watrter E. CoLLincE, M.Se., F.LS., ete, Research Fellow of the University of St Andrews, The Gatty Marine Laboratory, St Andrews.

Numerous abnormalities in the vascular system of the frog have been described by different observers, and probably a still greater number have been noticed, but not recorded. The series here described have all been met with during a period of about three years. A few occurred in the ordinary course of practical work in the zoological laboratory, but the majority have been found in the course of a large number of dissections made expressly for the purpose. Upwards of five hundred specimens have been examined and twenty-two abnormalities observed, the more important of which are here described.

Some of these are interesting as illustrating the persistence of embryonic stages, whilst some of the remainder may possibly be regarded as reversions to ancestral conditions.

No. 1.—In the developing frog we have present a median caudal continuation of the united posterior cardinal veins, usually known as the caudal vein. The lateral portion of these united cardinals ultimately forms the anterior part of the reni-portal veins of the adult and the median portion of the inferior vena cava, the caudal continuation disappearing.’ In the specimen here figured (fig. 1) the caudal vein has persisted, and is seen as a posterior prolongation of the inferior vena cava, which is continued backwards to the posterior boundary of the abdominal cavity.

No. 2.—This abnormality occurred on the left side of the body only. It is somewhat similar to one described by Shore,’ only rather more pronounced. The reni-portal vein is here continued forwards on the outer border of the kidney, and curving round the anterior end of that organ it opens directly into the inferior vena cava. From the posterior end of the kidney the vein gradually enlarges in size; after receiving two lumbar veins it becomes still more prominent, until at the anterior border of the

1 Gf. Milnes Marshall, Vertebrate Embryology, 1893, p. 184; also Shore, “On the Development of the Renal-Portals and Fate of the Posterior Cardinal Veins in the Frog,” Journ. of Anat. and Phys., 1901, vol. xxxvi. p. 37, fig. 14.

2 Shore, “ Unusual Arrangement of the Renal Portal Vein in the Frog,” Journ. of Anat. and Phys., 1900, vol. xxxiv. pp. 395-402. 38 Mr Walter E. Collinge

kidney it is quite double the normal size of this vein. I agree with Shore! that the most probable explanation of this abnormal vein “is that it is a persistent part of the left posterior cardinal vein, which normally disappears during the later parts of larval life.”

No. 3.—This interesting abnormality is probably to be explained in the same manner as No. 2, but curiously the left reni-portal vein is entirely absent. On the right side the femoral, sciatic, and pelvic veins are perfectly normal, the former two uniting as usual to form the reniportal vein, which, instead of passing to the outer border of the kidney, traverses the ventral surface of that organ, slightly posterior to its middle

Fic. 1.—Persistent caudal Fic. 2,—Abnormal reni- Fic. 3.—-Reni-portal vein convein. portal vein. tinuous with inferior vena cava.

and gives off two small veins to the substance of the kidney, and then passing forwards and towards the median line it enters directly into the inferior vena cava. On both right and left sides there are only three renal veins. The femoral on the left side is normal as far as the position where it should unite with the sciatic; but as there is no reni-portal on this side, the whole of the blood from both of these veins must be returned to the heart by way of the pelvic and anterior abdominal veins.

Nos. 4, 5, 6, and 7.—These four are all concerned with the reni-portal vein. In No. 4 the vein ‘bifurcates to form a loop before reaching the kidney as a single vein. In No. 5 a somewhat similar condition obtains, only there is a small commissure connecting the two sides. In No. 6 the bifurcation commences at the junction of the sciatic and femoral, so that

1 Op. cit., p. 401. Abnormal Developments in the Vascular System of the Frog 39

we might speak of two reni-portal veins on the left side. In No. 7 we have a very peculiar looping of the femoral, and the sciatic somewhat abnormal, but the chief interest in this specimen lies in the persistence of what might be described as the anterior portion of the right reni-portal. This I regard as a portion of the right posterior cardinal sinus, although there is no connexion anteriorly with the heart. In No. 8 we have this connexion.

No. 8.—In this specimen a vein branches from the anterior extremity of the right reni-portal vein, which latter vein is continued a little more anteriorly than usual. The vein passing from it traverses the body cavity

Fie, 4.—Looping of the Fic. 5.—Looping of the Fic. 6.—Double renireni-portal vein. reni-portal vein. portal vein. ~

on the right side and ultimately opens at the junction of the subclavian vein and the right anterior vena cava. Here again we have a persistence of the embryonic right posterior cardinal sinus.

Nos. 9 and 10.—These illustrate two most interesting cases in connexion with the anterior abdominal vein. Buller? has described a case somewhat. like No. 9. In this specimen the anterior abdominal vein is quite normal in the medio-ventral line of the abdominal wall; on reaching the region of the liver it joins with the hepatico-portal vein and a large branch is given off to the left lobe of the liver, but the right branch, a much finer one,

1 Cf Hochstetter, Morph. Jahrb., 1888, Bd. xiii., and Anat. Anzeiger, 1888 ; also Shore, op. ctt., 1901.

2 Buller, “ Abnormal Anterior Abdominal Vein in a Frog,” Journ. of Anat. and Phys., 1896, vol. xxx. pp. 211-214, fig. 40 Mr Walter E. Collinge

passes to the right superior vena cava. We undoubtedly have here the persistence of an embryonic character, but whether it also represents “a case of reversion to an ancestral stage, slightly in advance of that reached by Ceratodus, and therefore a case which, from its transitional character, tends to some extent to bridge over the gap between the Dipnoid and the normal Amphibia,” as assumed by Buller, I am not prepared to say, for the evidence is as yet far too imperfect. Baldwin Spencer! in his account

Fic. 7.—Abnormal femoral, sciatic, and Fic. 8.—Persistence of the embryonic right reni-portal veins. posterior cardinal sinus,

of the anterior abdominal vein of Ceratodus points out that it “ may in all ‘probability be rightly regarded as forming an anterior abdominal system comparable to that obtaining in Amphibia; though at the same time there are considerable differences between the two.”

In the normal development of the frog the right anterior abdominal vein always disappears before the left. Milnes Marshall,? describing this,

1 Baldwin Spencer, Contributions to our Knowledge of Ceratodus, pt. i. “The Bloodvessels” (Macleay Memorial Volume). 2 Op. cit., p. 184. Abnormal Developments in the Vascular System of the Frog 41

states: “The anterior abdominal vein is at first paired, and is in connexion, not with the liver, but the heart. The pair of vessels appear first in the ventral ‘body-wall, extending backwards a short distance from the sinus venosus ; they soon extend further backwards, and acquire communications with the veins of the hind legs and of the bladder. At a later stage the two anterior abdominal veins unite at their hinder ends, in front of the bladder, while further forwards the vein of the right side disappears, the left one alone persisting. Later still, the anterior abdominal vein loses its

taty exj

‘p

Fic. 9.—Persistence of the connexion with Fic. 10.—Persistence of the connexion with the heart of the anterior abdominal the heart of the anterior abdominal vein vein on the right side. on right and left sides.

direct communication with the sinus venosus, and acquires a secondary one with the hepatico-portal veins, or afferent veins of the liver.”

No. 10.—The occasional persistence in the adult frog of a condition such as is described above in the developing frog has long been suspected by those interested in the subject, but I am not aware that it has hitherto actually been observed.

Fig. 10 illustrates a case where this embryonic condition has persisted. Here the median anterior abdominal vein passes forwards in the normal manner. It has no connexion with the liver, but divides into right and left branches before reaching the region of that organ. These branches pass forwards one on each side and open into the right and left superior venz 42 Abnormal Developments in the Vascular System of the Frog

cavee respectively. On the right side the vein opens very close to the sinus venosus, but on the left side it is rather farther away.

Of the remaining abnormalities observed, two were identical with that described by Shore,! showing a connexion between the reni-portal and pulmonary veins. Two others showed a small vein entering the commencement of the anterior abdominal vein, just in front of the united pelvic

a.ab.

f.

Fig. 11.—Additional vein joining the Fic. 12,—Abnormal pelvic vein. anterior abdominal vein.

vein (fig. 11), which small vein was formed by two finer branches coming from the region of the bladder. In two other cases (fig. 12) the pelvic of the right side was formed by two branches from the femoral.

The remaining abnormalities were of only minor importance.

1 Op. cit., 1901, p. 324.

REFERENCE LETTERS.

a.ab, Anterior abdominal vein, _ t,s.v.c. Left superior vena cava. c. Caudal vein. p. Pelvic vein. ex.j. External jugular vein. | r. Renal veins. ft. Femoral. | rp. Reni-portal vein. h.-p. Hepatico-portal vein. | svc. Right superior vena cava. int.j. Internal jugular vein. sc. Sciatic vein. z.v.c. Inferior vena cava. | subel. Subclavian vein. k. Kidney. i sebse. Subscapular vein. L. Liver. s.v, Sinus venosus.

¢. Lumbar vein.