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A comparative study of the vas subintestinale in the vertebrates.

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A COMPARATIVE STUDY O F THE VAS
SUBINTESTINALE I N THE
VERTEBRATES
P A U L I N E KIMBALL
Department of Anatomy. New Pork University
NINE FIGURES
CONTENTS
Introduction ........................................................
A . General considerations ........................................
............
B. Scope of the present investigation . . . . . . . . . . . . .
C Material .....................................................
Present investigation ................................................
A Reptilia .....................................................
1 Chelonia (turtle) ......................................
2 Crocodilia (alligator) ..................................
3 . Squamata .............................................
Ophidia (snake) ....................................
Lacertilia (lizards) ...........
....................
B. Aves .................................
....................
1. Struthiones (ostrich) ..................................
2 . Gaviae (tern) ........................................
3 . Anseres (duck) ........................................
4 . Gallinae (grouse) ......................................
C Mammalia ...................................................
1. Marsupialia (opossum) ................................
2 . Carnivora (cat) .......................................
3 Insectivora (mole) .....................................
4 Edentata (armadillo) ..................................
5 Primates (man) .......................................
Conclusions and summary ............................................
Bibliography ........................................................
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371
373
374
375
376
376
377
379
379
379
380
380
381
382
383
383
383
384
386
387
388
389
393
397
INTRODUCTION
This investigation was concerned originally with the question as to whether o r not a subintestinal artery occurs during
the development of all of the mammals having an allantoic
371
THE A M E R I C A N J O U R N A L OF ANATOMY. VOL . 42. N O . 2
372
PAULINE KIMBALL
placenta. A subintestinal connection between the umbilical
and the omphalomesenteric arterial circulations has been
known for some years to occur in embryonic mice, rats, and
pigs, but apparently no effort has been made to find out
whether the occurrence of a subintestinal artery is exceptional
in these forms or characteristic of placental mammals in
general.
The question of the presence of a subintestinal artery in
man was raised by Senior ( '25) in his discussion of one type
of anomaly of the human umbilical artery. Anomalies reported by Kuliga ( '08) and Hafferl ( '19), Senior considered,
were examples of this type.
In a newborn infant described by Kuliga ('08), blood
reached the placenta through the coeliomesenteric artery.
This vessel, after giving off the usual intestinal branches,
left the mesentery to pass around the left side of the ileum
10 em. above the caecum to become continuous with the single
umbilical artery of the umbilical cord. Examination of the
hypogastric arteries revealed the absence of the intra-abdominal part of both arteries. Senior thought this anomalous
vessel consisted of three parts : a proximal portion (omphalomesenterit-:),a middle portion (a. subintestinalis), and a distal
portion (umbilical). This interpretation was strengthened
by Hafferl's description ('19) of an artery in a woman of
middle age which arose from one of the ileal branches of the
superior mesenteric artery and joined the right lateral umbilical ligament. It would appear in this case that the subintestinal artery had retained both its anterior and its posterior
connections and had loosened itself from the gut wall when
the gut began to lengthen.
To test Senior's hypothesis of the presence of a subintestinal artery in man, as well as its probable presence in the
embryos of all the Eutheria, the subintestinal artery was
sought in the embryos of all placental mammals of which
material of suitable age was available.
Upon consulting the literature, it was found that a subintestinal vein, although it has been described as occurring in
VAS SUBINTESTINALE IN T H E VERTEBRATES
373
all of the Anamia, has been found in only two of the Amniota,
the chick and the opossum. It has never been described in
Reptilia. It was decided to extend this investigation to include a study of the subintestinal vein in as many forms as
the material available would permit.
Since the a. subintestinalis and the V. subintestinalis are
identical as far as position is concerned, they are, no doubt,
homologous vessels. They differ only in their connections.
The name, vas subintestinale, is used to indicate their morphology ; the names a. subintestinalis and v. subintestinalis
are used to indicate their function.
A . General considerations
The primary vascular system of vertebrate animals consists of a median dorsal artery running dorsal to the alimentary canal and a ventral or subintestinal vein. I n animals in
which the anus is not terminal, that portion of this simple
longitudinal circulatory loop lying behind the anus is called
caudal (artery and vein), while the portion anterior to the
anus constitutes the v. subintestinalis. This type of vascular
system, which is almost completely retained by Amphioxus,
has been recognized for many years as making its appearance
in the embryos of Pisces and Amphibia.
The vas subintestinale is venous in the lower vertebrates,
but arterial in the vertebrates with an allantoic placenta, with
the possible exception of some Marsupialia (Perameles. Hill,
'97) and some of the Lacertilia (Scincid lizards),l in which
conditions have not been reported. The a. subintestinalis of
the higher vertebrates is, however, a true homologue of the
v. subintestinalis of the lower vertebrates. It is identical as
f a r as position is concerned, but its connections have ceased
to be venous and have become arterial. Position, it would
seem, rather than size or connections (and therefore function),
An allantoic placenta has been reported as present in the following Scincid
lizards : Chalcides tridactylis and C. ocellatus (Giocomini, '91), Tiliqua seincoides
(Flynn, '23)' Lygosoma entrecasteaux (Harrison and Weeks, ' 2 5 ) , L. (Hinulia)
quoyi, Egernia whitei, and E. striolata (Weeks, '27).
374
PAULINE KIMBALL
should be the criterion of individuality of the blood vessels
and of nomenclature. A comparative study of the formation
of blood vessels shows that it is not unusual for a welldetermined blood route connected in one way in one or more
forms to acquire new connections and to assume an entirely
different function in other forms.
The present investigation was undertaken at the suggestion of Prof. H. D. Senior, Department of Anatomy, New
York University. I wish to take this opportunity to thank
Professor Senior for his advice and criticism of this paper
and for the facilities he has placed at my disposal.
B. Scope of the presefit ifivestigatioN
As f a r as the original question as to whether o r not a
subintestinal artery occurs in all of the mammals with an
allantoic placenta is concerned, its presence is described in
Carnivora (cat), page 386 ; Insectivora (mole), page 387 ;
Edentata (armadillo), page 388, and Primates (man), page
359. Material for its study in Sirenia, Cetacea, and Cheiroptera has not been available.
Ravn ('94) was the first to describe a subintestinal connection between the umbilical and omphalomesenteric arteries
iii mammals. He observed this connection in rat and mouse
embryos and called it the 'omphalomesenteric artery. ' His
nomenclature is based on function-the fact that this vessel
transmits blood from the single umbilical artery to the yolk
prior to the time when the proximal part of the definitive
omphalomesenteric arteries are established.
The subintestinal position of this early connection between the umbilical
and the omphalomesenteric arteries entitles it to be regarded
in the morphological rather than in the physiological sense,
for it represents the embryonic subintestinal vein of the lower
vertebrate animals which in placental mammals has acquired
arterial connections.
Evans ('12) reported a similar arrangement in pig embryos
measuring 7.5 mm. to 9 mm., and Sabin ('17) was the first t o
VAS SUBINTESTINALE IN THE VERTEBRATES
375
apply the proper nomenclature-subintestinal artery-to this
arterial connection between the umbilical and the omphalomesenteric circulations. Evans merely makes a statement of
the existence of this vessel, while Sabin gives a detailed
account of it.
Bartfeld ('25) observed an arterial connection which he
called the ' rete periintestinale caudale ' between the omphalomesenteric and the umbilical arterial systems in Talpa europea
(mole). He did not associate this 'rete' with the vas subintestinale. It is doubtful that he is familiar with Sabin's
work ( '17), for he makes no reference to it in his paper.
The v. subintestinalis, as f a r as is known, has never been
described in Reptilia. A description of this vessel in Chelonia
(turtle), Lacertilia (lizard), Ophidia (snake), and Crocodilia
(alligator) is given, pages 376 to 380.
A subintestinal venous connection between the omphalomesenteric and umbilical circulations has been described in
Aves (chick) by Hochstetter ( '88). Other writers, notably
Lillie ( '08), Evans ( '09), and Sabin ( W ) , have also described it. Sabin's account is the most complete. As f a r as
is known, it has not been described in any other bird. A description of it as it occurs in Struthio (ostrich), Anas (duck),
Bonasa (grouse), and Sterna hirundo (tern) is given, pages
380 to 383.
The subintestinal vein has not been described as occurring
in the monotremes. It has been reported t o be present in
one of the marsupials (opossum) by Senior ( '25).
C. Material
The material used in making this investigation was obtained
from the following embryological collections :
California Embryological Collection (C. E. C.).
Carnegie Institution Embryological Collection (C. I. E. C.).
Harvard University Embryological Collection (H. E. C. ).
Huntington Embryological Collection, Columbia University
(Hun. E. C.).
Texas Embryological Collection (T. E. C.).
Wistar Institute Embryological Collection (W. I. E. C.).
~
376
PAULINE KIMBALL
I wish to express my appreciation and thanks to
Profs. H. $1. Evans, G. L. Streeter, J. L. Bremer, A. Elwyn,
and J. T. Patterson, and Dr. M. J. Greenman for their generosity in placing their material at my disposal.
The embryos studied were for the most part cut either into
cross or longitudinal sections. Wax reconstructions were
made from drawings of the sections projected t o scale by the
Edinger apparatus. In the case of the Evans human embryo,
no. 168, graphic and celluloid reconstructions were made from
photographs of cross-sections of the embryo.
PRESENT INVESTIGATION
A . Reptilia
A subintestinal vein has never been described in Reptilia.
Ruckert (’06) bases much of his account of the early yolk
vessels in Reptilia upon Strahl’s study of Lacerta. At the
stage of development illustrated in Hertwig’s Handbuch, figure 870, the area vasculosa resembles that of a similar stage
in selachians. It will be noticed, however, that there is no
curving upward of the venous net in the caudal portion of
the embryo. Ruckert calls attention to this fact and points
out that the external ring vein is not connected with the
vessels (subintestinal veins) within the posterior part of the
body of the embryo.
Figure 871 (Hertwig’s Handbuch) is that of a little later
stage, showing the appearance of the aa. vitellinae. These are
very numerous. They are lateral branches of the aorta and
arise ab initio. They are “in toto homolog den dorso-ventralen Darmgefassen der Amphibien, die von der Aorta hinab
zum Dotter ziehen.”
It is of interest to call attention to a certain description by
Harrison and Weeks (’25) of the fetal blood circulation in
Lygosoma entrecasteauxi ( Scincid lizard). These fetuses
measured 30 to 40 mm. They state, “as the yolk-stalk is fol
lowed outwards, it is seen that a second and smaller vitelline
vein enters the umbilical vein.”
VAS SUBINTESTINALE I N THE VERTEBRATES
377
The Scincid lizards are peculiar in that they have both a
yolk-sac placenta and an allantoic placenta. The former
precedes the latter, both phylogenetically and ontogenetically.
Later, they fuse to form a common stalk containing the yolk
and allantoic vessels.
The writer offers this interpretation of Harrison and
Weeks ’ description : A subintestinal connection does occur
between the two circulations when the two placentae are
separate. Later, when the yolk and allantoic stalks fuse to
form a common yolk-allantoic stalk, the subintestinal vein is
carried out with the vessels of each stalk, so that “as the
yolk-stalk is followed (outward, it is seen that a second and
smaller vitelline vein enters the umbilical vein” (the umbilical
and omphalomesenteric veins are single). I n this case, the
subintestinal vein is not involved in the formation of the later
gut vessels, as is the case in the other vertebrates, but is
carried out in toto into the stalk where it remains throughout
fetal life in its primitive condition.
It is to be regretted that material f o r the study of the complete history of the v. subintestinalis in each of the orders,
Chelonia, Crocodilia, and Squamata, is not available.
2 . Chelouzia. Four embryos of Thalassoclrelys (loggerhead
turtle) examined have a v. subihtestinalis. They are no. 826
(8.5 mm.), no. 827 (9 mm.), no. 841 (10 mm.), and no. 842
(10 mm.) of the Hun. E. C. All have undergone incubation
for eleven days.
The subintestinal vein is collapsed in spots in no. 826 (8.5
mm.) and no. 827 (9 mm.). These embryos resemble no. 841
(10 mm.), which was reconstructed, and are of interest because they serve as a guide to the time and length at which
the subintestinal vein appears.
The subintestinal vein in turtles is double at first, but later
becomes single. No. 842 (10 mm.) has a double subintestinal
vein which extends posteriorly from the yolk sac more than
half the length of the hind gut. Anteriorly, each of these
veins opens separately onto the yolk; posteriorly, they coalesce to form a single channel, which soon splits at the cloaca
to join the subcardinal veins.
378
PAULINE KIMBALL
The condition of the subintestinal vein in no. 841 (10 mm.)
is a little further advanced than in the embryo just described.
The wax reconstruction of the posterior end of this embryo
(fig. 1)shows that the v. subintestinalis is a single continuous
channel. It arises from the peri-anal ring just anterior to
the cloaca and ventral to the hind gut. The subcardinal veins
swing around the hind gut to join the peri-anal ring laterally.
Fig. 1 Reconstruction of loggerhead-turtle embryo, no. 841, Hun. E. C., 10 mm.,
11 days. X 16.6.
Two allantoic veins from the allantois join the peri-anal ring
just anterior to the latter. As the subintestinal vein is traced
forward along the ventral surface of the gut, it tends to lie
t o the left. There is a short right subintestinal vein near the
yolk sac which the reconstruction of this region revealed.
This vessel is very short and is closely related to the left subintestinal vein by numerous cross branches. Apparently, this
vessel is being rapidly displaced by the left subintestinal vein.
VAS SUBINTESTINALE I N THE VERTEBRATES
379
The postcardinal veins are present ; but the subintestinal
vein is not related to these veins as in Aves, but are related
to the subcardinal veins.
2. Crocodilia. The v. subintestinalis is present in an embryo
of Alligator mississippiensis, no. 1504, H. E. C. (4 mm.). This
embryo is of interest in that it is the youngest reptilian
embryo examined. A subintestinal vein (fig. 2 ) arises from
each of the two allantoic veins at the junction of the allantois
with the hind gut. They run forward ventral to the gut and
soon coalesce to form a single vein which, upon reaching
the yolk, joins a tributary of the left omphalomesenteric vein.
Fig. 2
Reconstruction of alligator embryo, no. 1504, H. E. C., 4 mm.
X 16.6.
The postcardinal veins a r e present, but are difficult t o see
in some of the sections. They extend posteriorly from the
sinus venosus as very thin thread-like vessels and are not
related in any way to the subintestinal venous system. No
trace of the subcardinal veins could be found.
3. Squamnta. Ophidia. Two embryos of the snake, Eutaenia radix (H. E. C.) were examined, and both have a subintestinal vein. They are no. 1348 (5.8 mm.) and no. 1361
(6 mm.).
The reconstruction of no, 1348 (5.8 mm.) shows a subintestinal vein ventral to the hind gut. A large caudal vein is
present, but it is collapsed at the point where it should join
380
PAULINE KIMBALL
the subintestinal vein. The subintestinal vein is easily followed from the cloaca posteriorly to the yolk anteriorly, where
it opens out upon the yolk (fig. 9, A ) .
The postcardinal veins are present anteriorly, but have not
yet reached the peri-anal ring posteriorly.
Lacertilia. Four specimens of Lacertilia (H. E. C.) belonging to two different genera, Lacerta muralis and Iguana
tuberculata, were found to have a subintestinal vein. The
two embryos of Lacerta muralis are no. 827 (6.4 mm.) and
no. 815 (6.4 mm.) ; the two embryos of Iguana tuberculata
were no. 1540 (6.5 mm.) and no. 1532 (6.1 mm.).
In no. 815 (6.4 mm.) the peri-anal venous ring is formed
posteriorly by the caudal vein, laterally by the postcardinals
and subcardinals, and anteriorly by the subintestinal vein
which runs forward ventral to the hind gut toward the yolk.
In no. 827 (6.4 mm.) a similar arrangement of the vessels
occurs. The actual termination of the subintestinal vein in
the omphalomesenteric veins is a little more clearly shown.
I n no. 1532 (6.1 mm.) the posterior relation of the subintestinal vein could not be determined accurately, owing to
the collapse of the vessel; it terminates in the conjoined omphalomesenteric veins.
The subintestinal vein and its connections in no. 1540 (6.5
mm.) resembles that of no. 1532 (6.1 mm.).
B. Aves
Popoff ( '94), through injection, determined the nature of
the blood vessels on the area vasculosa of the chick. The area
vasculosa resembles that of the reptiles. Both the sinus terminalis (rand Sinus) and the internal ring veins (innere
Randvene) are venous. Two yolk-gut veins (vv. vitellinae
laterales) derived from the internal ring veins collect the
blood from tbe vascular network at the sides and above the
head. Two yolk arteries (aa. vitellinae laterales) connect
the aorta with the yolk. The left yolk vein appears to be
the larger of the two yolk veins, for, in addition t o draining
the left half of the area va'sculosa, it received two large
VAS SUBINTESTINALE I N T E E VERTEBRATES
381
branches, the anterior vitelline vein from the cephalic portion
of the vascular net and posterior vitelline vein from the
caudal portion of the vascular net.
Aves, in addition to having a well-developed yolk sac, have
a large allantois with a well-developed circulation.
Hochstetter ('88) was the first to notice a subintestinal
connection between the allantoic and the omphalomesenteric
venous circulations. Lillie ( 'OS), Evans ( '09), and Sabin
('17) have described this vessel.
According to Sabin, the subintestinal vein appears on the
third day of incubation. It develops out of an extensive
plexus which surrounds the gut. At first there are two veins,
a right and a left, but these soon coalesce to form a single
vein. The subintestinal vein a t this stage receives the most
caudal branches of the posterior limb bud (Evans) and drains
the entire posterior end of the gut, the allantois, the rectum,
and the intestine up to the yolk sac (Sabin).
As to the fate of the subintestinal vein in the chick, Sabin
says that, after the umbilical circulation appears on the fourth
day, the subintestinal vein ceases to be a single channel and
develops into the plexus in the wall of the gut.
The presence of the v. subintestinalis in four additional
species of Aves-Struthio
(ostrich), Sterna hirundo (tern),
Anas (duck), and Bonasa (grouse)-is of interest and of
value from a comparative standpoint, f o r there can now be
little doubt but that the v. subintestinalis is present in the
embryos of all birds. I n the stages examined of all of these
forms the subintestinal vein is at the height of its development. The enormous size of the subintestinal vein in
Struthio and in Anas is most striking. A comparison of the
subintestinal vein in these forms with the same vessel in the
chick shows it to be at least five times as great.
1. Struthiones. Reconstruction of Struthio (ostrich) no.
2236 (H. E. C., 7.2 mm.) (fig.3 ) shows the subintestinal vein
to be the direct continuation of the single allantoic vein which
runs along the dorsal wall of the allantoic stalk to the junction of the allantois with the hind gut. At this point the
-
382
PAULINE KIMBALL
vessel turns to continue ventral to the gut as the subintestinal
vein. Upon reaching the yolk sac, it joins a branch of the
left omphalomesenteric vein.
The postcardinal veins have taken over the caudal vein and
the veins of the posterior limb in this embryo. The subcardinal veins have not yet appeared. The dorsal roots of the
umbilical arteries are present.
2, Gauiae. I n an embryo of Sterna hirundo (tern), no. 2167
(H. E. C., 5 mm.), there are two allantoic veins present. The
reconstruction shows the subintestinal vein arising from the
anastomosis of the two allantoic veins, which occurs ventral
to the juncture of the cloaca with the allantoic stalk. The
subintestinal vein runs forward ventral t o the hind gut from
this point to the yolk sac, where it enters a branch of the left
omphalomesenteric vein. The two caudal veins do not join
the subintestinal vein in this embryo, f o r the postcardinal
venous system has reached the peri-anal ring and has taken
over the drainage of the tail and posterior limbs.
VAS SUBINTESTINALE I N THE VERTEBRATES
383
The subcardinal veins appear in the region of the fore part
of the hind gut, but have not yet reached as far as the perianal ring.
3. Anseres. The subintestinal vein was observed in two
duck embryos (Anas) (H. E. C.), no. 2194 (95 hours) and
no. 2195 (104 hours). I n the older embryo the subintestinal
vein arises in the usual way-from the anastomosis of the
two allantoic veins and runs forward ventral to the gut. The
two caudal veins join the two allantoic veins on either side of
the cloaca, thus forming the peri-anal ring from which the
subintestinal veins arise. The postcardinal veins have taken
over the drainage of the posterior limb. There are no subcardinal veins present in the region of the peri-anal ring.
Figure 9, B, is a photomicrograph of a cross-section of this
embryo. The enormous size of the subintestinal vein is of
interest. It is much larger in Anas and Struthio than in the
chick. The way in which it bulges from the ventral wall of
the hind gut resembles the state of the a. subintestinalis in
Ravn’s case, thus suggesting the possibility of separation
from the gut wall.
4. Gallinae. I n an embryo of Bonasa (grouse), no. 2215
(H. E. C., 7.3 mm., 97 hours), the subintestinal vein arises
from the peri-anal ring formed by the anastomosis of the
two caudal veins with the two allantoic veins. It runs forward
ventral to the hind gut and terminates in a branch of the left
omphalomesenteric vein.
The postcardinal venous system has taken over the drainage of the posterior limbs.
C. Marnrnalia
The area vasculosa of the mammals differs from that of
the other vertebrates in that it is more highly arterial. The
innere Randvene remains venous, just as it does in all of the
other vertebrates, as far as is known, except elasmobranchs ;
the sinus terminalis, which is venous in all of the other vertebrates, becomes arterial in the mammals. During the earlier
stages of development there are numerous aa. vitellinae as in
384
PAULINE HIMBALL
reptiles, but soon the number is reduced to two aa. vitellinae
laterales or t o one, the single a. vitellina media.
The vas subintestinale has been reported t o be a vein in
Marsupialia (Senior, '25) and an artery in Rodentia (Ravn,
'94) and Ungulata (Evans, '12, and Sabin, '17). An arterial
rete periintestinale caudale has been described in Insectivora
(Bartfeld, '25).
Nothing more need be said about the work of Ravn, Evans,
and Bartfeld than has already been mentioned on page 375.
Further mention of Sabin's work is necessary.
Sabin states that the subintestinal artery of the pig arises
from ventral branches of the aorta whieh form a sheet of
capillaries on either side of the alimentary canal. This vessel
is apparently well developed in a pig embryo of 20 somites
and can be seen in these embryos as late as 9 or 10 mm. After
the caudal flexure has formed, the subintestinal artery breaks
up into the capillary plexus within the wall of the gut. I n
15- to 17-mm. embryos a new longitudinal artery appears in
the dorsal wall of the gut and takes over the work of the
subintestinal artery.
The mammals are peculiar in that the vas subintestinale
may be a vein o r an artery, depending upon the connections
which it established. The presence of an allantoic placenta
is apparently instrumental in causing the vas subintestinale
to become an artery. It is to be regretted that material is
not available t o study the complete history of the vas subintestinale in all the mammalian orders. Material, however,
is available for the study of its complete history in the cat.
1. Marsupialia. Senior ('25) reported the presence of the
subintestinal vein in opossum embryo, no. 16174, W. I. E. C.
(6.92 mm.), but did not describe the vessel or its connections.
A subintestinal vein is present in that embryo and in no.
16173, W. I. E. C. (7.6 mm.). These embryos are of about the
same age; the 7.6-mm. embryo is perhaps a little younger than
the 6.92-mm. embryo. I n both of them the subintestinal vein
is in the process of being transformed into a plexus in the
wall of the gut. Posteriorly, the subintestinal vein has lost
385
VAS SUBINTESTINALE I N THE VERTEBRATES
its connection with the umbilical veins and has become plexiform; anteriorly, it remains as a single vessel' which terminates in a branch of the omphalomesenteric vein.
No. 16173 (7.6 mm.) is especially favorable f o r tracing the
subintestinal vein to its termination in the yolk vein and for
following the yolk vein to its termination in the right omphalo-
lsl"larnl.rir.
i".li.
x
Fig. 4
16.6.
Reconstruction of opossum embryo, no. 16174, W.I. E.C., 6.92 mm.
mesenteric vein near its junction with the left omphalomesenteric vein.
No. 16174 (6.92 mm.) was reconstructed not because it was
the most favorable embryo for study, but because it came
into my possession before no. 16173 (7.6 mm.). Figure 4 illustrates the condition of the other arteries and veins as well
as that of the subintestinal vein in the region of the hind gut.
386
PAULINE KIMBALL
Examination of figure 4 shows that the postcardinal veins
have joined the peri-anal ring and have taken over the drainage of the hind limbs. The subcardinal veins have appeared
anteriorly in the region of the anterior part of the hind gut.
The connection between the postcardinal veins and the subcardinal veins is seen in figure 4.
2. Carnivora. Abundant material was available for study
of the complete history of the vas subintestinale in the eat
(Hun.E. C.). Embryos ranging from 3.5 mm. to 8.5 mm.
were examined.
Fig. 5 Reconstruction of mole embryo, no. 990, Hun. E. C., 4 mm.
x
16.6.
I n no. 687 (3.5 mm.) and no. 135 (4.5 mm.), the subintestinal
artery is double. I n these specimens the two subintestinal
arteries arise on either side from a series of ventral roots of
each umbilical artery. These arteries run forward ventral
and lateral to the hind gut to the yolk sac, where they join
the omphalornesenteric arteries.
The youngest embryo reconstructed which contains a single
subintestinal artery is no. 889 (6 mm.). The subintestinal
artery (fig. 5) arises posteriorly from the peri-anal ring. The
umbilical arteries arise by several ventral roots and assist
in the formation of the peri-anal ring. The dorsal root of
each umbilical artery is present, but very small. Several
ventral-gut vessels arising from the aorta join the subintestinal artery posteriorly.
VAS SUBINTESTINALE I N THE VERTEBRATES
387
The second reconstruction made was that of no. 261
(6.5 mm.). I n this embryo the subintestinal artery is no
longer connected with the umbilical arteries posteriorly. The
subintestinal artery a t this stage receives all of its blood from
the ventral-gut vessels, several of which can be seen posteriorly. The subintestinal artery, as a single channel, could
be traced to its termination in the omphalomesenteric arteries
f o r at least three-fourths the length of the hind gut. Figure 9,
C, is a photomicrograph of this vessel as it appears in a
cross-section taken through the fore part of the hind gut.
No. 752 (7 mm.) contains the largest subintestinal artery,
as far as actual diameter of the vessel is concerned. The
posterior connection with the umbilical circulation by means
of the ventral root has entirely disappeared. This specimen
appears to be in practically the same stage of development
as no. 261 (6.5 mm.).
The last trace of the subintestinal artery is found in no. 285
(8.5 mm.). The anterior connection of the subintestinal artery with the omphalomesenteric is still present and can be
traced to the yolk sac postero-anteriorly for nineteen sections. This embryo is in the same stage of development as
the opossum embryo, no. 16174 (6.92 mm.).
3. Insectivora. The three mole embryos (Hun. E. C.) examined have a pair of subintestinal arteries. They are no. 402
(3.5 mm.), no. 407 (3.5 mm.), and no. 990 (4mm.).
The reconstruction of no. 990 (4 mm.) shows two subintestinal arteries arising from the peri-anal arterial ring (fig. 6).
These arteries run forward parallel to each other and ventral
to the hind gut, to terminate in the omphalomesenteric arteries, where they anastomose before forming a loop about
the gut on their way to the aorta. The ventral roots of the
umbilical arteries are very small; no dorsal roots have yet
appeared.
Upon examining the literature, it was found that Bartfeld
('as), in Bis account of the development of the gut arteries of
Talpa europea, described a ' rete periintestinale caudale ' arterial connection between the umbilical and omphalomesenTHE AXERICAN JOURNAL O F ANATOMY, VOL.
42,
NO.
2
388
PAULINE KIMBALL
teric circulations. Examination of figures 6 and 7 of his
paper shows a reconstruction of this ‘rete.’ Judging from
these figures, the most ventral vessel of this gut plexus must
be the subintestinal artery. The umbilical arteries arise from
the aorta by several ventral roots (fig. 6). The subintestinal
artery takes origin from these ventral roots and runs forward
to the yolk (fig. 7). This arrangement of the vessels, as
shown in Bartfeld’s figures, corresponds very much to the
arrangement which the writer has observed in the cat embryo,
no. 889, 6.5 mm. (fig. 5).
Fig. 6
Reconstruction of cat embryo, no. 889, Hun. E. C., 6 mm.
X 16.6.
Bartfeld compares this ‘rete periintestinale caudale’ of the
mole with a similar ‘rete’ which he found in pig (Bartfeld,
fig. 15). Bartfeld’s bibliography contains a reference t o
Evans’ work ( ’12, Keibel and Mall), but since Evans’ description of the ventral ‘arterial route’ in pig occurs in one of the
footnotes, it is possible that Bartfeld did not see it. There is
no reference to Sabin’s work in his bibliography.
4. Edentata. The armadillo embryos are of special interest,
because the subintestinal artery has separated itself from
the hind gut and lies a short distance ventral to, and connected
with, the gut by a short thread-like mesentery (fig. 9, D).
The embryos are no. 275, no. 356 A, and no. 356 B (T. E. C.).
The two latter embryos are litter mates.
VAS SUBINTESTINALE I N THE VERTEBRATES
389
The subintestinal artery in all three of these embryos is
about to be transformed into a plexus in the wall of the gut.
It is plexiform posteriorly, while anteriorly it persists as a
single vessel which terminates in the conjoined omphalomesenteric arteries.
No. 275 is a little younger than no. 356A and no. 356B.
I n this embryo it is possible to trace the anterior persisting
portion of the subintestinal artery f o r more than half the
length of the hind gut. Figure 9, D, is a photomicrograph of
a cross-section of this embryo. The thin thread-like mesentery which connects the subintestinal artery with the hind gut
is readily observed. I n some sections this mesentery appears
t o have been lost, but this could not be positively determined.
The subintestinal artery in no. 356A and no. 356B is
almost completely transformed into a plexus in the wall of
the hind gut. Only a short, degenerated anterior portion
terminating in the conjoined omphalomesenteric arteries remains. These embryos are older than any of the other mammalian embryos studied. The yolk sac is retracted into the
abdomen ; the omphalomesenteric circulation is greatly re
duced and is on the verge of disappearing (probably nonfunctional) ; the allantoic circulation is now the functioning
circulation (the dorsal roots of the umbilical arteries are
very large ; the ventral roots have disappeared).
5. Primates. The study of the subintestinal artery in man
met with the usual difficulty-absence of suitable material.
Consequently, numerous embryos had t o be examined before
the proper material for making this investigation could be
found. All the embryos which were likely to have a subintestinal artery from the Carnegie Institution of Washington,
Cornell University Medical College, Huntington Collection of
Columbia University, Harvard Medical School, and photographs of one embryo, the Evans embryo, no. 168, of the
University of California Embryological Collection were
examined.
No. 836 (C. I. E. C., 4 mm., 30 somites) was the youngest
embryo studied (fig. 7 ) . I n this embryo the a. subintestinalis
390
PAULINE KIMBALL
is double f o r the posterior two-thirds of the length of the
hind gut. It arises on either side from the ventral roots of
each umbilical artery. The dorsal root is present, but is very
small. The hind gut is very short in this embryo. The two
subintestinal arteries join just before the hind gut begins to
widen out to become continuous with the yolk sac. On either
side and ventral to this neck there is an arterial plexus. The
/---
A
Fig. 7
Reconstruction of human embryo, no. 836, C. I.E. C., 4 mm.
X 16.6.
right plexus appears to be in the process of being formed;
the left plexus is by far the most prominent, and it is through
this plexus that the subintestinal artery can be traced to its
termination in the left omphalomesenteric artery.
No. 1075 (C. I.E. C., 6 mm.) is only a little older than no.
836 (4mm.). According to Streeter, the arm buds are more
distinct, the tail longer, and the lungs are a shade further
along. The vas subintestinale (fig. 8) is double for almost
VAS SUBINTESTINALE I N T H E VERTEBRATES
391
the entire length of the hind gut. These vessels arise posteriorly on either side from the ventral root of the umbilical
artery, run forward parallel to each other and ventral to
the hind gut to the yolk sac, where they anastornose before
Fig. 8
16.6.
joining the omphalomesenteric arteries. The dorsal roots
of the umbilical arteries are present, but are very small in
comparison to the ventral roots.
The Evans embryo, no. 168 (C. E. C., Japanese), is considerably older than either no. 836 or no. 1075. Several reconstructions, based on the photographs of cross-sections of
392
PAULINE KIMBALL
this embryo, were made-celluloid, graphic, and a wax model
of a few of the sections taken through the region of junction
between the subintestinal artery and the left omphalomesenteric artery.
This embryo is of interest from a comparative standpoint,
for the vas subintestinale is in the same stage of its developmental history as the opossum embryo (6.92 mm.), the cat
embryo (8.5 mm.), and the armadillo embryo-the phase of
its disappearance. I n this embryo the subintestinal artery
is plexiform in the posterior three-fourths of the hind gut
and exists as a single channel anteriorly, where it joins the
left omphalomesenteric artery. The ventral roots of the
umbilical arteries are no longer present; the dorsal roots are
quite large and are now the functional roots.
CONCLUSIONS AND SUMMARY
The history of the vas subintestinale is now practically
complete. There can be no doubt that the v. subintestinalis
and the a. subintestinalis are morphologically the same vessel.
Their position is identical, only their connections differ.
The presence of an allantoic placenta is apparently the
factor which determines whether the vas subintestinale shall
be a vein or an artery. With the reduction of the yolk-sac
circulation, the allantoic circulation is necessarily increased.
I n making this change the arterial system appears to outstrip
the venous system in development. This results in an extensive arterial peri-anal ring, which gives rise to the a. subintestinalis. Sabin ('17) calls attention to the fact that in the
gut of the pig the arteries precede the veins.
Based upon the study of the a. subintestinalis in the cat,
of which abundant material was available for the study of its
complete history in this form, it can be said that three stages
are recognizable in the developmental history of the vas subinntestinnabis. Whether with respect to vein or artery, all of
the embryos studied fall in one or another of these three
stages.
VAS SUBINTESTINALE I N THE VERTEBRATES
393
I n the first stage the vas subintestinale consists of a pair
of vessels, one on either side and ventral to the hind gut.
Examples of this stage have been mentioned: v. subintestinalis-turtle (no. 842, Hun. E. C., 10 mm.) ; a. subintestinalis
-cat (no. 687, 3.5 mm., and no. 135, 4.5 mm., Hun. E. C.),
mole (no. 402, 3.5 mm., no. 407, 3.5 mm., and no. 990, 4 mm.,
Hun. E. C.), and man (no. 836, 4 mm., and no. 1975, 6 mm.,
C. I. E. C.).
The second stage may be regarded as the stage at which
the vas subintestinale is at the height of its development. In
this stage the two paired vessels coalesce to form a single
channel. The best examples of this stage are: v. subintestinalis-turtle (no. 841, 10 mm., Hun. E. C.), alligator (no. 1504,
4 mm., H. E. C.), snake (no. 1348, 5.8 mm., H.E. C.), ostrich
(no. 2236, 7.2 mm., H.E. C.), tern (no. 2167, 5 mm., H.E. C.),
duck (no. 2194 and no. 2195, H. E. C.), and grouse (no. 2215,
7.5 mm., H. E. C.); a. subintestinalis-cat (no. 889, 6 mm.,
Hun. E. C.).
The third stage consists of the stage of transformation of
the vas subintestinale. I n the adult the v. subintestinalis is
retained in some forms as the vein of the spiral valve. I n
Amphibia, Reptilia, Aves, and the lower Mammalia it develops into the plexus in the wall of the gut. The a. subintestinalis has a similar fate.
When the vas subintestinale begins to transform, the posterior portion breaks up first ; the anterior portion is retained
(v. subintestinalis as a branch of v. omphalomesenteria; a.
subintestinalis as a branch of a. omphalomesenteria). Examples of this stage are : v. subintestinalis-opossum
(no.
16174,6.92 mm., W. I. E. C.) ; a. subintestinalis-cat (no. 285,
8.5 mm., Hun. E. C.), armadillo (no. 275, no. 356 A, no. 356 B,
T. E. C.), and man (no. 168, C. E. C.).
Previous writers, notably Hochstetter ( '88, subintestinal
vein, chick) and Sabin ('17, subintestinal artery, pig), have
described the first two stages in the development of the vas
subintestinale, i.e., stage I, double vas subintestinale ; stage
11, single subintestinale. Evidently, no previous writer has
394
PAULINE KIMBALL
observed that the anterior portion of the vas subintestinale is
retained f o r quite a period of time after the posterior portion
has been lost.
The tendency for the vas subintestinale to produce a bulge
in the wall of the gut has been pointed out and can be observed
Y
#"#I
6
Fig. 9 Photomicrographs showing the subintestinal vein in cross-section. x 25.
A, snake embryo, no. 1348, H. E. C., 5.8 mni. B, duck embryo, no. 2195, H. E. C.,
104 hours. C , cat embryo, no. 261, Hun.E.C., 6.5 mm. D, armadillo embryo,
no. 275, T.E.C.
in the photomicrographs (fig. 9). Actual separation of this
vessel from the wall of the gut has been observed in the armadillo. These observations lend weight to the suggestion made
by Senior ( '25) that the anomaly reported by Kuliga ('08)
was due to the disappearance of the proximal part of both
umbilical arteries and the retention of the subintestinal artery
VAS SUBINTESTINALE I N THE VERTEBRATES
395
by the proximal part of the omphalomesenteric artery and
the anomaly reported by Hafferl ( ’19), which Senior thought
was due to the retention of the a. subintestinale in toto without loss of any part of the umbilical arteries.
It is suggested that in the Scincid lizards a subintestinal
venous connection exists between the omphalomesenteric and
umbilical venous circulations when the yolk stalk and the
allantoic stalk are separate and spring separately from the
intestine. Later, when the yolk stalk and the allantoic stalk
fuse t o form a common yolk-allantoic stalk, the subintestinal vein is carried out in toto into this common yolkallantoic stalk, so that “as the yolk-stalk is followed outward,
it is seen that a second and smaller vitelline vein enters the
umbilical vein” (Harrison and Weeks, ’25).
The peculiarity of the Reptilia in the precocious development of the subcardinal veins has been noted. These veins
seem to develop almost synchronously with the postcardinals.
The result of such an arrangement is that the subintestinal
vein takes origin from these veins instead of the postcardinals, as in Marsupialia and Aves.
On the following page is a tabular summary of the results
of the present investigation and those of previous investigators.
396
PAULINE KIMBALL
REPTILIA:
Thalassochelgs (caretta)
No. 826, 8.5 mm., 11days
No. 827, 9 mm., 11days
No. 841, 10 mm., 11days
No. 842, 1 0 mm., 11days
Lacerta muralis
No. 827, 6.4 mm.
No. 815, 6.1 mm.
Iguana tubwculata
No. 1540, 6.5 mm.
No. 1532, 6.1 mm.
Eutaenia radix
No. 1348, 5.6 mm.
No. 1361, 6 mm.
Alligator mississippiensis
No. 1504, 4 mm.
AVES:
Gallus domtsticus
Struthio
No. 2236, 7.2 mm.
Anas
No. 2194, 3 days, 2 1 hours
No. 2193, 4 days, 8 hours
Bonasa
No. 221.5, 4 days, 1 hour,
7.3 mm.
Sterna hirundo
No. 2167, 5 mm.
MAMMALIA:
Didel phis virginiuna
No. 16174, 6.92 mm.
Nus (rat and mouse)
Sus scrofa
7.5 t o 9 mm.
20 somit es to 9 or 1 0 mm.
Talpa mropaea
No.990, 4mm.
Felis domesticus
No. 687, 3.5 mm.
No. 135, 4.5 mm.
No. 889, 6 mm.
No. 261, 6.5 mm.
No. 752, 7 mm.
No. 285, 8.5 mm.
Tatusia
No. 356 A
No. 356 B
No. 275
Homo sapiens
No. 1075, 6 mm.
No. 836, 4mm.
No. 168
Collection
Vessel
Author
H.E. C.
Vein
Kimball
H.E. C.
Vein
Kimball
H.E. C.
Vein
Kimball
H.E. C.
Vein
Kimball
€1. E. C .
Vein
Kimball
H.E. C .
Vein
Vein
Hochstetter ( '88)
Eimball
H . E . C.
Vein
Kimball
H.E.C.
Vein
Kimball
H.E. C.
Vein
Kimball
W. I. E.C .
Vein'
Senior ( '25)
Artery
Ravn ( '94)
Artery
Artery
Rete caudalis
Hun. E. C . Artery
Hun. E. C. Artery
Evans ( '12)
Sabin ( '17)
Bartfeld ( '25)
Kimball
Rimball
T. E. C.
Artery
Kimball
C. I. E. C.
Artery
Kimball
C. E. C.
VAS SUBINTESTINALE IN THE VERTEBRATES
397
BIBLIOGRAPHY
S. 1925 Zui. Entwicklungsgeschichte der Darmarterien der WirbelBARTFELD,
tiere.
Die Entwicklungsgeschichte der Darmarterien bei Talpa
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EVANS,
H. M. 1909 On the development of the aorta, cardinal and umbilical
veins and other blood vessels of the vertebrate embryos from capillaries.
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1912 The development of the vascular system. Manual of Human
Embryology, edited by Keibel and Mall, vol. 2, p. 657.
FELrx, W. 1910 Zur Entwicklungsgeschichte der Rumpfarterien des menschlichen Embryo. Morph. Jahrb., Bd. 41, Heft 4, S. 577-614.
FLYNN,
T. T. 1923 On the occurrence of a true allanto-placenta of the conjoint
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GIACOMINI,E. 1891 Materiaux pour 1'6tude du dbveloppement dn Septs chal.
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1891 Uber die Entwickelung von Septs chalcides. Anat. Anz.,
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- 1906 Sulla maniera di gestazione e sugli annessi embrionali del
Gongylus ocellatus. Forsk. Mem. Accad. Bologna, ser. 6, 111.
pp. 131-175.
HAFFERL,A. 1919 Uber ein Fall von Persistenz der Arteria omphalomesenterica. Zeits. f. angew. Anat. u. Eonstitutionsl., Bd. 4, S. 292-297.
AND WEEKS 1925 On the occurrence of placentation in the Scincid
HARRISON
lizard, Lygosoma entrecasteauxi. Proc. Linn. Soe. N. S. W., vol. 1,
pp. 472-486.
HILL, J. P. 1900 On the foetal membranes, placentation and parturition of
the native cat (Dasyurus viverrines). Anat. Ana., Bd. 18, S. 364-373.
1897 The placentation of Perameles. Quart. Journ. Micr. Sci.,
vol. 40, no. 159, pp. 385-447.
HOCHSTETTER,
F. 1888 Beitrage zur Entwicklungsgeschichte des Venensystems
der Amnioten. Morph. Jahrb., Bd. 13, S. 575-586.
1893 Entwicklungsgeschichte des Gefasssystems. Ergebnisse d.
Anat. und Entw., Bd. 3, S. 460-489.
1906 Die Entwiekelung des Blutgefasssystems. Handbuch d. vergl.
u. exp. Entw.-lehre d. Wirbeltiere, Bd. 3, pl. 2, S. 111-149.
EULIGA,
P. 1905 Uber Sirenenmissbildung und ihre Genese. Monatssch. f.
Geburtsh. u. Gynak., Bd. 27, 8. 297-321.
LILLIE,F. R. 1908 The development of the chick, p. 367.
PATTEN,
B. M. 1925 Embryology of the chick, p. 367.
POPOFF,
D. 1894 Die Dottersack-Gefasse des Huhnes. Wiesbaden.
RAVN,E. 1894 Uber die Arteria omphalo-mesenterica der Ratten und Mause.
Anat.'Anz., Bd. 9, S. 420-424.
RAFFAELE,
F. 1888 Le uova galleggianti e le larve die Teleostei nel golfo di
Napoli. Mitth. a. d. Zoolog. Stat. zu Neapel, Bd. 8, 5. 1-85.
RUCKERT,
J., UND MOLLIER,6. 1906 Die erste Entstehung der Gefasse und des
Blutes bei Wirbeltieren. Handb. d. vergl. u. exp. Entw.-lehre d. Wirbeltiere, herausg. von 0. Hertwig, Bd. 1, T. 2, S. 1019-1273.
398
PAULINE KIMBALL
SABIN, F. R. 1917 Origin and development of the primitive vessels of the
chick and of the pig. Contrib. t o Embryol., Carnegie Inst. Washington,
vol. 6, no. 18, pp. 61-125.
SEMON,R. 1894 Die Embryonalhiillen der Monotremen und Marsupialier.
Zool. Forschungsreisen in Australien u.s.w., Bd. 2, S. 19-58.
SENIOR,H. D. 1909 The development of the heart in shad (Alosa sapadissima,
Wilson). Am. Jour. Anat., vol. 9, no. 2, pp. 211-262.
1925 An interpretation of the recorded arterial anomalies of the
human pelvis and thigh. Am. Jour. Anat., vol. 36, no. 1, pp. 1-47.
STRAHL, H. 1382 BeitrLge zur Entwickelung von Lacerta agilis. Arch. f.
Anat. u. physiol. Anat., S. 242-279.
1883 Beitrage zur Entwickelung der Reptilien. Ebenda, S. 1-40.
TANDLER,J. 1903 Zur Entwickelungsgeschichte der menschlichen Darmarterien.
Anat. Hefte, Bd. 23, S. 187-209.
WEEKS, H. C. 1927 A note on reproductive phenomena in some lizards. Proc.
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