Difference between revisions of "Paper - Studies of the intestine and peritoneum in the human foetus - part 1"

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=Studies of the Intestine and Peritoneum in the Human Foetus. Part I=
  
=Studies Of The Intestine And Peritoneum In The Human Foetus. Part I=
 
  
 
By Douglas G. Reid, M.B., Ch.B. Edin., B.A. Trin. Coll. Camb.,  
 
By Douglas G. Reid, M.B., Ch.B. Edin., B.A. Trin. Coll. Camb.,  
Line 33: Line 33:
  
  
STUDIES OF THE INTESTINE AND PERITONEUM IN THE
+
These studies are based chiefly on the examination of the arrangement of the peritoneum in twenty fetuses in the Cambridge Museum (of which nine were female specimens), varying in length from 12 to 20 cms. (vertex-coccygeal measurement).
HUMAN FCETUS. PART I. By DOUGLAS G. REID, M.B., Ch.B.
 
  
Edin., B.A. Trin. Coll. Can'1b., Demonst7°cLt07° of Ambtomy in the
 
Univermty of C'wmZn°idge.
 
  
THESE studies are based chiefly on the examination of the arrangement
 
of the peritoneum in twenty ftfetuses in the Cambridge Museum (of which
 
nine were female specimens), varying in length from 12 to 20 cms. (vertex-coccygeal measurement).
 
  
In this part I shall describe a peritoneal fold present in eleven (six
+
In this part I shall describe a peritoneal fold present in eleven (six males and five females) of the twenty foetuses (55 per cent.). Moreover, there is evidence of its having been present at an earlier stage in at least three others. In order to understand the changes accompanying the presence of this fold, it is necessary to refer to the line of the root of the foetal mesentery. Except in the case of the part fixed to the front of the fourth portion (ascending part of the pars inferior) of the duodenum, the root of the mesentery is attached along a line which is still practically transverse. It is implanted upon the whole of the front of the third portion (transverse part of the pars inferior) of the duodenum, and to the right of this upon the peritoneum covering ‘the front of the right kidney. It to be noted that the root is attached to the posterior abdominal wall exactly along the line of the ileo—colic artery which arises from the superior mesenteric at (never below) the place where this artery crosses the third portion of the duodenum, and courses towards the right. At this stage the surfaces of the mesentery may be described as being superior and inferior. Indeed, the mesentery lies often horizontally for some distance from its root, forming a shelf, supported on its inferior surface by the large intra-abdominally placed pelvic colon. One notes here that the retro—colic fossa in the adult is limited medially by a fold, the 1nesenterico—iliac fold of Jonnesco (plica genito-enterica of Treitz). This is described as being merely the insertion of the mesentery in the iliac fossa, where it has a very variable line of insertion, in the female being continuous (always?) with the broad ligament. The special genito-mesenteric fold (see fig. 1) which I now describe passes downwards from the inferior surface of the mesentery in the right half of the abdomen.
males and five females) of the’ twenty foetuses (55 per cent.). Moreover,
 
there is evidence of its having been present at an earlier stage in at least
 
three others. In order to understand the changes accompanying the
 
presence of this fold, it is necessary to refer to the line of the root of the
 
foetal mesentery. Except in the case of the part fixed to the front of
 
the fourth portion (ascending part of the pars inferior) of the duodenum,
 
the root of the mesentery is attached along a line which is still practically
 
transverse. It is implanted upon the whole of the front of the third portion
 
(transverse part of the pars inferior) of the duodenum, and to the right of
 
this upon the peritoneum covering ‘the front of the right kidney. It to
 
be noted that the root is attached to the posterior abdominal wall exactly
 
along the line of the ileo—colic artery which arises from the superior
 
mesenteric at (never below) the place where this artery crosses the third
 
portion of the duodenum, and courses towards the right. At this stage
 
the surfaces of the mesentery may be described as being superior and
 
inferior. Indeed, the mesentery lies often horizontally for some distance
 
from its root, forming a shelf, supported on its inferior surface by the large
 
intra-abdominally placed pelvic colon. One notes here that the retro—colic
 
fossa in the adult is limited medially by a fold, the 1nesenterico—iliac fold
 
of Jonnesco (plica genito-enterica of Treitz). This is described as being
 
merely the insertion of the mesentery in the iliac fossa, where it has a
 
very variable line of insertion, in the female being continuous (always?)
 
with the broad ligament. The special genito-mesenteric fold (see fig. 1)
 
which I now describe passes downwards from the inferior surface of the
 
mesentery in the right half of the abdomen.
 
  
There is nothing corresponding to it on the left side. It forms an antero—posterior septum lying in the vertical plane, incompletely subdividing the portion of the abdominal cavity below the root of the mesentery
 
into two compartments. The smaller of these is to its right side, and contains the caecum; the larger is to its left side, and contains the pelvic
 
colon. The fold is, as it were,.propped up on the sides by these portions of the bowel.
 
  
 +
There is nothing corresponding to it on the left side. It forms an antero—posterior septum lying in the vertical plane, incompletely subdividing the portion of the abdominal cavity below the root of the mesentery into two compartments. The smaller of these is to its right side, and contains the caecum; the larger is to its left side, and contains the pelvic colon. The fold is, as it were,.propped up on the sides by these portions of the bowel.
  
  
FIG. 1.—Fcetus No. XI.
+
FIG. 1. Foetus No. XI.
  
  
 +
The fold is triangular in form. It presents right and left surfaces, both of which are generally free. Of its borders, two are attached: one, the posterior, to the posterior abdominal wall along the line of the right spermatic or ovarian vessels; and the other, the superior or mesenteric, to the inferior surface of the mesentery, often to a considerable extent.
  
The fold is triangular in form. It presents right and left surfaces,
 
both of which are generally free. Of its borders, two are attached: one,
 
the posterior, to the posterior abdominal wall along the line of the right
 
Studies of the Intestine and Peritoneum in the Human Foetus 75
 
  
spermatic or ovarian vessels; and the other, the superior or mesenteric,
+
The ileac branch of the ileo-colic artery leaves the fold, in which it lies at the root of the mesentery (to be described later), and courses forwards, away from the posterior abdominal wall, in the substance of the mesentery.
to the inferior surface of the mesentery, often to a considerable extent.
 
  
The ileac branch of the ileo-colic artery leaves the fold, in which it lies
 
at the root of the mesentery (to be described later), and courses forwards,
 
away from the posterior abdominal wall, in the substance of the mesentery.
 
  
 
 
  
 +
FIG. 2. Foetus No. XIV.
  
FIG. 2.—Foetus No. XIV.
+
The attachment of the genito-mesenteric fold to the mesentery is generally exactly along the line of this artery. The anterior border of the fold is in most cases free. It is usually continuous below with the suspensory ligament of the ovary, and its inferior extremity appears in consequence truncated. This fold is not to be confounded with a mere dihedral angling of the mesentery, in relation to the ileac branch of the ileo-colic artery, although in some instances the ileum may become adherent to its right side. This adhesion may occur close to the ovary, which thus comes (as in one foetus) to be intimately bound to the ileum. The uniting band here is evidently not a pathological adhesion. However, the continuity of the fold with the suspensory ligament of the ovary is not constant; the two folds may be separate, although lying in line one above the other.
  
The attachment of the genito-mesenteric fold to the mesentery is generally
 
exactly along the line of this artery. The anterior border of the fold is
 
in most cases free. It is usually continuous below with the suspensory
 
ligament of the ovary, and its inferior extremity appears in consequence
 
truncated. This fold is not to be confounded with a mere dihedral angling
 
of the mesentery, in relation to the ileac branch of the ileo-colic artery,
 
although in some instances the ileum may become adherent to its right side.
 
This adhesion may occur close to the ovary, which thus comes (as in one
 
foetus) to be intimately bound to the ileum. The uniting band here is
 
76 . Mr Douglas G. Reid
 
  
evidently not a pathological adhesion. However, the continuity of the fold
+
In the male foetuses the fold is not usually continued into the suspensory ligament of the testis—although it may reach to this—saVe through the prominence produced by the spermatic vessels descending behind the peritoneum of the posterior abdominal wall.
with the suspensory ligament of the ovary is not constant; the two folds
 
may be separate, although lying in line one above the other.
 
  
In the male foetuses the fold is not usually continued into the suspensory
 
ligament of the testis—although it may reach to this—saVe through the
 
prominence produced by the spermatic vessels descending behind the
 
peritoneum of the posterior abdominal wall.
 
  
In the full-time foetus (fig. 3), in which the genito-mesenteric fold is
+
In the full-time foetus (fig. 3), in which the genito-mesenteric fold is present, the parts have acquired almost the position which they occupy in the adult, the caecum lying in the right iliac fossa, and the hepatic and splenic flexures in their usual adult position. But the whole of the ascending and transverse colon is free of attachment to the posterior abdominal wall, as is the 1nesentery of the ascending colon, jejunum, and ileum. All ca11 be pulled freely forward. In other words, almost the whole of the peritoneum of the intestinal loop is free. The caecuin having completed its descent, the ileo-colic vessels new take a definitely descending course, in the free peritoneum of the loop, towards the ileo-czecal junction. They lie in the obvious folds of peritoneum, along the line of which the root of the mesentery is usually attached. Had the peritoneum of the intestinal loop become soldered down at these folds, the line of the root of the mesentery would have followed exactly the direction usually taken in the adult. It is true that the root of the mesentery passes down upon the fourth portion of the duodenum; but this is the primitive condition, this part of the duodenum belonging to the intestinal, and not to the duodenal loop. The anterior surfaces of the first, second, and third portions of the duodenum are free (5.0. the peritoneum of the intestinal loop and the transverse colon can be pulled forwards off these parts). The first and second parts of the duodenum are also free behind, as is the posterior surface of the meso—duodenum and the head of the pancreas. But although the peritoneum of the intestinal loop, save where it covers the front of the meso—duodenum, is free of adhesion, on lifting the loop forwards the large triangular genito-mesenteric fold is seen passing from the posterior surface of its peritoneum backwards to the posterior abdominal wall.
present, the parts have acquired almost the position which they occupy in
 
the adult, the caecum lying in the right iliac fossa, and the hepatic and
 
splenic flexures in their usual adult position. But the whole of the
 
ascending and transverse colon is free of attachment to the posterior
 
abdominal wall, as is the 1nesentery of the ascending colon, jejunum, and
 
ileum. All ca11 be pulled freely forward. In other words, almost the
 
whole of the peritoneum of the intestinal loop is free. The caecuin having
 
completed its descent, the ileo-colic vessels new take a definitely descending
 
course, in the free peritoneum of the loop, towards the ileo-czecal junction.
 
They lie in the obvious folds of peritoneum, along the line of which the
 
root of the mesentery is usually attached. Had the peritoneum of the
 
intestinal loop become soldered down at these folds, the line of the root of
 
the mesentery would have followed exactly the direction usually taken in
 
the adult. It is true that the root of the mesentery passes down upon
 
the fourth portion of the duodenum; but this is the primitive condition,
 
this part of the duodenum belonging to the intestinal, and not to the
 
duodenal loop. The anterior surfaces of the first, second, and third portions
 
of the duodenum are free (5.0. the peritoneum of the intestinal loop and the
 
transverse colon can be pulled forwards off these parts). The first and
 
second parts of the duodenum are also free behind, as is the posterior
 
surface of the meso—duodenum and the head of the pancreas. But although
 
the peritoneum of the intestinal loop, save where it covers the front of the
 
meso—duodenum, is free of adhesion, on lifting the loop forwards the large
 
triangular genito-mesenteric fold is seen passing from the posterior surface
 
of its peritoneum backwards to the posterior abdominal wall.
 
  
The Whole appearance is one of a remarkable T—shaped mesentery
 
holding down the intestine, and taking the place of the normal root of the
 
mesentery.
 
  
The fold extends downwards to the posterior (internal) abdominal ring.
+
The whole appearance is one of a remarkable T—shaped mesentery holding down the intestine, and taking the place of the normal root of the mesentery.
The mesenteric border is attached to the duodenum at the angle between
 
the second and third portions——and it is here that the duodenum descends
 
lowest in the abdomen—as well as to the peritoneum of the intestinal loop
 
along a line 3.8 cms. long.
 
  
  
 
+
The fold extends downwards to the posterior (internal) abdominal ring. The mesenteric border is attached to the duodenum at the angle between the second and third portions——and it is here that the duodenum descends lowest in the abdomen—as well as to the peritoneum of the intestinal loop along a line 3.8 cms. long.
  
This line lies to the right of the ileo-colic artery above, but lower down it
 
passes directly along the ileac branch of this vessel, as in the other foetuses.
 
The fold, therefore, would have become reduced in size if the intestinal loop
 
and its peritoneum had become soldered down to the normal extent. The
 
part of the fold related to the ileac branch, along which adhesion does not
 
occur, would, however, have remained.
 
  
Its posterior border, from the duodenum downwards to the internal
 
abdominal ring, is 6'4: cms. long. The anterior, or free, border measures
 
  
   
+
This line lies to the right of the ileo-colic artery above, but lower down it passes directly along the ileac branch of this vessel, as in the other foetuses. The fold, therefore, would have become reduced in size if the intestinal loop and its peritoneum had become soldered down to the normal extent. The part of the fold related to the ileac branch, along which adhesion does not occur, would, however, have remained.
  
FIG. 3. —Drawn with careful measureliients from a full-time fmtus. 'l‘wo~thi1'ds actual size. Viewed
 
from the right side. The artery is -.1 branch of the right gastro-epiploic (not figured).
 
  
7.5 cms. in length. The mesenteric border lies an average distance of 2 cms.
 
from the ascending colon, and a large number of lacteal glands lie in the
 
mesentery along the ileac artery. The surfaces of the fold are free, and
 
between their endothelial laminae are many lymphatic glands and a network of blood-vessels, visible to the naked eye. The portion of the great
 
omentum to the right of the pylorus (ac. the right process of the great
 
omentum) extends downwards upon the colon as far as the root of the
 
appendicular caecum. A branch of the right gastro—epiploic artery, lying in
 
this, extends upon the colon to the hepatic flexure (see fig.  It then leaves the great omentum and passes over the posterior surface of the upper part of the ascending colon and comes to lie in the mesocolon. Leaving this, it crosses the lower part of the second portion of the duodenum, and gets on to
 
the posterior abdominal Wall, to the right side of the fold. After a curved
 
course, it enters the genito-mesenteric fold at its posterior border, and finally
 
emerging from the fold at its mesenteric border, again enters the mesentery,
 
and ends on the colon near the caecum.
 
The spermatic vessels lie along the parietal attachment of the fold.
 
Although the second portion of the duodenum is free behind, a thin
 
sheet of peritoneum (see fig. 3) passes from its right border to the front of
 
the right kidney. This sheet lies in a vertical and antero-posterior plane,
 
and its right endothelial lamina is continuous with the corresponding lamina
 
of the genito-mesenteric fold. A
 
s As will be seen from the foregoing description of the duodenum, it
 
forms the right boundary of a large retro—duodenal fossa, which opens
 
above at the foramen of Winslow into the general peritoneal cavity. It
 
presents at the level of the junction of the first and second portions of the
 
duodenum a superior free horizontal edge stretching from the duodenum
 
to the kidney. The upper part of this sheet, therefore, is simply the
 
  
_duodeno-renal ligament.‘ *
+
FIG. 3.  Drawn with careful measureliients from a full-time fmtus. two-thirds actual size. Viewed from the right side. The artery is -.1 branch of the right gastro-epiploic (not figured).
  
The vessels ramifying upon the anterior surface of the second portion of
 
the duodenum are not so distinctly visible as those seen upon the front of the
 
first portion. This is due to the presence of a peritoneal veil which passes from
 
the posterior surface of the peritoneum of the intestinal loop over the front
 
of the second part of the duodenum, to be continuous with the peritoneal
 
sheet, which anchors the right border of the duodenum to the kidney. This
 
veil is also continuous below, like the sheet itself, with the right endothelial
 
lamina of the genito-mesenteric fold.
 
  
Certain modifications were found in the line of attachment of the
+
Its posterior border, from the duodenum downwards to the internal abdominal ring, is 6.4: cms. long. The anterior, or free, border measures 7.5 cms. in length. The mesenteric border lies an average distance of 2 cms. from the ascending colon, and a large number of lacteal glands lie in the mesentery along the ileac artery. The surfaces of the fold are free, and between their endothelial laminae are many lymphatic glands and a network of blood-vessels, visible to the naked eye. The portion of the great omentum to the right of the pylorus (ac. the right process of the great omentum) extends downwards upon the colon as far as the root of the appendicular caecum. A branch of the right gastro—epiploic artery, lying in this, extends upon the colon to the hepatic flexure (see fig. It then leaves the great omentum and passes over the posterior surface of the upper part of the ascending colon and comes to lie in the mesocolon. Leaving this, it crosses the lower part of the second portion of the duodenum, and gets on to the posterior abdominal Wall, to the right side of the fold. After a curved course, it enters the genito-mesenteric fold at its posterior border, and finally emerging from the fold at its mesenteric border, again enters the mesentery, and ends on the colon near the caecum. The spermatic vessels lie along the parietal attachment of the fold. Although the second portion of the duodenum is free behind, a thin sheet of peritoneum (see fig. 3) passes from its right border to the front of the right kidney. This sheet lies in a vertical and antero-posterior plane, and its right endothelial lamina is continuous with the corresponding lamina of the genito-mesenteric fold. A s As will be seen from the foregoing description of the duodenum, it forms the right boundary of a large retro—duodenal fossa, which opens above at the foramen of Winslow into the general peritoneal cavity. It presents at the level of the junction of the first and second portions of the duodenum a superior free horizontal edge stretching from the duodenum to the kidney. The upper part of this sheet, therefore, is simply the duodeno-renal ligament.
  
' mesentery in foetuses in which the genito-mesenteric fold is present, as
 
  
well as some examples of visceral adhesions to the fold.
+
The vessels ramifying upon the anterior surface of the second portion of the duodenum are not so distinctly visible as those seen upon the front of the first portion. This is due to the presence of a peritoneal veil which passes from the posterior surface of the peritoneum of the intestinal loop over the front of the second part of the duodenum, to be continuous with the peritoneal sheet, which anchors the right border of the duodenum to the kidney. This veil is also continuous below, like the sheet itself, with the right endothelial lamina of the genito-mesenteric fold.
  
Without an actual alteration in the line of the root of the mesentery
 
occurring, a deep fossa is present in one foetus on the upper surface of
 
the F mesentery, the bottom of the fossa corresponding to the line of
 
attachment of the genito-mesenteric fold.
 
  
In two foetuses the ileo-colic artery to the right of the duodenum forms
+
Certain modifications were found in the line of attachment of the mesentery in foetuses in which the genito-mesenteric fold is present, as well as some examples of visceral adhesions to the fold.
the base of a triangle, the apex of which is below, and the sides of which
 
are placed at the root of the mesentery. The genito-mesenteric fold is
 
attached to the mesentery opposite the apex (73.6. opposite the most depressed
 
part of the mesenteric root). .
 
  
Again, in two others, although the root of the mesentery retains its
 
intimate relation to the ileo-colic artery to the left side of the fold, the
 
  
1 For a good figure of this see Spalteholz’s Atlas. A
+
Without an actual alteration in the line of the root of the mesentery occurring, a deep fossa is present in one foetus on the upper surface of the F mesentery, the bottom of the fossa corresponding to the line of attachment of the genito-mesenteric fold.
Studies of the Intestine and Peritoneum in the Human Foetus 79
 
  
ileum, in the last 1'5 cms. and 2 cms. of its course, adheres firmly, along
 
with the whole of its mesentery, to the peritoneum of the posterior
 
abdominal wall to its right side, and the ileum also adheres to the right
 
surface of the fold itself. In one of these foetuses the mesentery indeed
 
is also tacked down slightly to the abdominal Wall on the left side of the
 
  
fold. In this foetus the ileac artery is placed in a fold of peritoneum,
+
In two foetuses the ileo-colic artery to the right of the duodenum forms the base of a triangle, the apex of which is below, and the sides of which are placed at the root of the mesentery. The genito-mesenteric fold is attached to the mesentery opposite the apex (73.6. opposite the most depressed part of the mesenteric root).
J quite 3 mms. high, Which is seen projecting from the upper surface of the
 
  
mesentery. This arterial fold, since it lies over the genito-mesenteric
 
fold, owes its existence to this tacking down of the mesentery on both
 
sides. It forms a veritable septum, subdividing the marked fossa resulting
 
  
. from this depression of both laminae of the mesentery into a right and left
+
Again, in two others, although the root of the mesentery retains its intimate relation to the ileo-colic artery to the left side of the fold, the ileum, in the last 1'5 cms. and 2 cms. of its course, adheres firmly, along with the whole of its mesentery, to the peritoneum of the posterior abdominal wall to its right side, and the ileum also adheres to the right surface of the fold itself. In one of these foetuses the mesentery indeed is also tacked down slightly to the abdominal Wall on the left side of the fold. In this foetus the ileac artery is placed in a fold of peritoneum, J quite 3 mms. high, Which is seen projecting from the upper surface of the mesentery. This arterial fold, since it lies over the genito-mesenteric fold, owes its existence to this tacking down of the mesentery on both sides. It forms a veritable septum, subdividing the marked fossa resulting from this depression of both laminae of the mesentery into a right and left part. In these, and in another foetus, the ileum adheres definitely to the right side of the genito-mesenteric fold, whose connection with the mesentery is still distinctly seen.
  
part. In these, and in another foetus, the ileum adheres definitely to the
 
right side of the genito-mesenteric fold, whose connection with the mesentery
 
is still distinctly seen.
 
  
"In two other foetuses the genito-mesenteric fold passes from the non-mesenteric border of the terminal portion of the ileum, and has no apparent
+
* 1 For a good figure of this see Spalteholz’s Atlas.  
connection with the mesentery. p .
 
  
But, in the light of all the other instances, there is little doubt that in
 
these cases the ileum had first of all adhered by one of its aspects to the
 
right side of the fold. Through great solidity of soldering of the peritoneal
 
surfaces together, this surface of the ileum became again apparently free.
 
  
I have seen a comparably great solidity of fusion in the case of the great
 
omentum, which on this account may appear, even before birth, to have
 
partially disappeared. It may be seen also in the case of the appendix.
 
  
Thus in one foetus the genito-mesenteric fold passes from the usually
+
"In two other foetuses the genito-mesenteric fold passes from the non-mesenteric border of the terminal portion of the ileum, and has no apparent connection with the mesentery.
free border of the appendix, and does not appear to be continued over the
 
appendix to the mesentery. °
 
  
The appendix is connected to the mesentery by a sheet of peritoneum
 
(see fig. 4:, A), which at first sight appeared to be simply meso-appendix.
 
But the clue to its real nature is found in the fact that, when viewed from
 
the left (see fig. 4), the artery of the appendicular caecum (Which occupies
 
a distinct fold along the free edge of the meso-appendix) seems suddenly to
 
disappear, becoming suddenly obscured by a peritoneal veil. But when
 
viewed from the right the artery is distinctly visible to the usual extent.
 
The front edge of this veil is continued into the free edge of a sheet of peritoneum above the artery, and thereby passes to the inferior surface of the
 
mesentery. These appearances leave no doubt that not only had the serous
 
  
 +
But, in the light of all the other instances, there is little doubt that in these cases the ileum had first of all adhered by one of its aspects to the right side of the fold. Through great solidity of soldering of the peritoneal surfaces together, this surface of the ileum became again apparently free.
 +
 +
 +
I have seen a comparably great solidity of fusion in the case of the great omentum, which on this account may appear, even before birth, to have partially disappeared. It may be seen also in the case of the appendix.
 +
 +
 +
Thus in one foetus the genito-mesenteric fold passes from the usually free border of the appendix, and does not appear to be continued over the appendix to the mesentery.
 +
 +
 +
The appendix is connected to the mesentery by a sheet of peritoneum (see fig. 4:, A), which at first sight appeared to be simply meso-appendix. But the clue to its real nature is found in the fact that, when viewed from the left (see fig. 4), the artery of the appendicular caecum (Which occupies a distinct fold along the free edge of the meso-appendix) seems suddenly to disappear, becoming suddenly obscured by a peritoneal veil. But when viewed from the right the artery is distinctly visible to the usual extent. The front edge of this veil is continued into the free edge of a sheet of peritoneum above the artery, and thereby passes to the inferior surface of the mesentery. These appearances leave no doubt that not only had the serous coat of the appendix adhered to the right side of the genito-mesenteric fold, a condition seen in another foetus, but that one surface of the meso-appendix, from border to border, had also similarly adhered. Here again the appendix, save at its borders, appears free of the fold; and the explanation of this condition appears to be that it results from solidity of soldering.
  
coat of the appendix adhered to the right side of the genito-mesenteric fold, a condition seen in another foetus, but that one surface of the
 
meso-appendix, from border to border, had also similarly adhered. Here
 
again the appendix, save at its borders, appears free of the fold; and the explanation of this condition appears to be that it results from solidity of soldering.
 
  
 
A similar arrangement in connection with the appendix and meso-appendix was found in an adult male. Here a slight fold passed downwards upon the external iliac vessels from the usually free border of the appendix. The fold, then, which connected the appendix to the mesentery in these cases is the result of the fusion together of two sheets of peritoneum, and represents genito-mesenteric fold on the left and meso—appendix on the right.
 
A similar arrangement in connection with the appendix and meso-appendix was found in an adult male. Here a slight fold passed downwards upon the external iliac vessels from the usually free border of the appendix. The fold, then, which connected the appendix to the mesentery in these cases is the result of the fusion together of two sheets of peritoneum, and represents genito-mesenteric fold on the left and meso—appendix on the right.
Line 287: Line 120:
  
  
+
FIG. 4. Fcetus No. X.
 +
 
 +
 
 +
We have seen that, in association with the genito-mesenteric fold, the ileum and its mesentery may become adherent to the posterior abdominal wall on the right side of the fold. Similarly, the caecum may become adherent to the posterior abdominal wall on this side. Thus, in one foetus the caecum, its appendix, and the meso-appendix, and with it the “blood-less ” fold of Treves, are firmly soldered down to the abdominal wall on the right side of the genito-mesenteric fold ; and the “ bloodless fold ” was similarly seen directly adherent to the posterior abdominal wall in associa- tion with this fold. It is essentially on the right of the fold, as well as actually to the right surface of the fold itself, that these adhesions occur.
 +
 
  
 +
In only three cases is the genito-mesenteric fold associated with a retro-colic fossa. But in most of the foetuses in which it is present the appendix is definitely retro-colic.
  
FIG. 4.—Fcetus No. X.
 
  
 +
The genito-mesenteric fold appears to be late in making its appearance, if one can. judge from its absence in a 25-mm. foetus (given to me by Mr John Griffith, B.-A., of Christ’s College). a How this fold is produced is not clear. It is possible that sometimes the right extremity of the great omentum (which is late in appearing) may assist in forming it, perhaps extending in some cases off the colon on to the posterior abdominal wall, and fusing, as it does so, with the right surface of the fold. The presence of the branch of the right gastro-epiploic artery in the fold—and indeed projecting, rather from’ its right surface, as if it had been added on—-and behind the peritoneum of the posterior abdominal wall might thus be explained. It is difficult to see why its mesenteric border should be related to the ileac branch of the ileo-colic artery?
  
We have seen that, in association with the genito-mesenteric fold, the
 
ileum and its mesentery may become adherent to the posterior abdominal
 
wall on the right side of the fold. Similarly, the caecum may become
 
adherent to the posterior abdominal wall on this side. Thus, in one foetus
 
the caecum, its appendix, and the meso-appendix, and with it the “blood-less ” fold of Treves, are firmly soldered down to the abdominal wall on
 
the right side of the genito-mesenteric fold ; and the “ bloodless fold ” was
 
similarly seen directly adherent to the posterior abdominal wall in associa-
 
tion with this fold. It is essentially on the right of the fold, as well as
 
actually to the right surface of the fold itself, that these adhesions occur.
 
  
In only three cases is the genito-mesenteric fold associated with a
+
The fold may exercise considerable influence on parts about it. It is significant that the lowest point of the duodenum is at the place of attachment of this fold. This suggests that it exerts a traction upon the duodenum at this part. If this traction be excessive, it may be a cause of downward displacement of the duodenum.
retro-colic fossa. But in most of the foetuses in which it is present the
 
appendix is definitely retro-colic.
 
  
The genito-mesenteric fold appears to be late in making its appearance,
 
if one can. judge from its absence in a 25-mm. foetus (given to me by
 
Mr John Griffith, B.-A., of Christ’s College). a How this fold is produced is
 
not clear. It is possible that sometimes the right extremity of the great
 
omentum (which is late in appearing) may assist in forming it, perhaps extending in some cases off the colon on to the posterior abdominal wall, and
 
fusing, as it does so, with the right surface of the fold. The presence of the
 
branch of the right gastro-epiploic artery in the fold—and indeed projecting,
 
rather from’ its right surface, as if it had been added on—-and behind the
 
peritoneum of the posterior abdominal wall might thus be explained. It
 
is difficult to see why its mesenteric border should be related to the ileac
 
branch of the ileo-colic artery? T '
 
  
The fold may exercise considerable influence on parts about it. It
+
The second part of the duodenum may also adhere to the left side of the fold.
is significant that the lowest point of the duodenum is at the place of
 
attachment of this fold. This suggests that it exerts a traction upon the
 
duodenum at this part. If this traction be excessive, it may be a cause of
 
downward displacement of the duodenum. ..
 
  
The second part of the duodenum may also adhere to the left side of
 
the fold.
 
  
The duodeno-renal sheet and veil of peritoneum already described
+
The duodeno-renal sheet and veil of peritoneum already described were formed by the upper part of the genito-mesenteric fold. We may also infer from this foetus that the duodeno-renal ligament of Huschke is practically the upper part of the fold.
were formed by the upper part of the genito-mesenteric fold. We may also
 
  
infer from this foetus that the duodeno-renal ligament of Huschke is
 
  
practically the upper part of the fold.
+
In the light of these specimens, and associated with the elongation of the ascending colon and the descent of the genital gland, this fold is evidently a cause of depression and actual tacking down of the mesentery, with a consequent lowering of the mesenteric root, with which the ileo-colic artery may retain or lose, to a greater.or less degree, its close relation.  
  
In the light of these specimens, and associated with the elongation of
 
the ascending colon and the descent of the genital gland, this fold is
 
evidently a cause of depression and actual tacking down of the mesentery,
 
  
with a consequent lowering of the mesenteric root, with which the ileo-colic I
+
The fold may also assist in producing adhesion of the duodenum, caecum, and ileum to the posterior abdominal Wall. Adhesion in the adult binding down the terminal part of the ileum, the caecum, the appendix, the mesentery, the meso—appendix, and even the “bloodless” fold of Treves, need not be the result of pathological changes, unless the natural cause We have indicated for the adhesion can be excluded, although a genito-mesenteric fold may not always be seen even in the foetus.
  
artery may retain or lose, to a greater.or less degree, its close relation.
+
The ovary may be bound, sometimes very intimately, to the ileum or appendix, through the adhesion of these parts of the bowel to the right surface of the fold.
VOL. XLV. (THIRD smn. VOL. VI.)——JAN. 1911. 6
 
82 Mr Douglas G. Reid
 
  
The fold may also assist in producing adhesion of the duodenum, caecum,
 
and ileum to the posterior abdominal Wall. Adhesion in the adult binding down the terminal part of the ileum, the caecum, the appendix, the
 
mesentery, the meso—appendix, and even the “bloodless” fold of Treves,
 
need not be the result of pathological changes, unless the natural cause
 
We have indicated for the adhesion can be excluded, although a genito-mesenteric fold may not always be seen even in the foetus.
 
  
The ovary may be bound, sometimes very intimately, to the ileum or
 
  
 
 
 
 
 
 
 
  
  
FIG. 5.—-Foetus No. XVIII. Part of the side wall of the abdomen has been removed.
+
FIG. 5. Foetus No. XVIII. Part of the side wall of the abdomen has been removed.
  
appendix, through the adhesion of these parts of the bowel to the right
 
surface of the fold.
 
  
There is no “ general shifting of the endothelial layers in such a manner
 
that What was once free peritoneal surface remains free,” 1 apparently produced by the genito-mesenteric fold in determining these adhesions.
 
  
Its action upon the mesentery is to render a part of it. more immobile ;
+
There is no general shifting of the endothelial layers in such a manner that What was once free peritoneal surface remains free, apparently produced by the genito-mesenteric fold in determining these adhesions.
and through it, apparently, a traction is exerted upon the mesentery.
 
  
The genito-mesenteric fold must be of considerable interest from a
 
surgical and gynaecological point of view. Its adhesion may restrict the’
 
  
1 “ Morphology of the Digestive Tract,” by Byron Robinson, M.D., Joum. 0] Anat. and
+
Its action upon the mesentery is to render a part of it. more immobile ; and through it, apparently, a traction is exerted upon the mesentery.
Phys., xxxiii.
 
  
 +
The genito-mesenteric fold must be of considerable interest from a surgical and gynaecological point of view. Its adhesion may restrict the spread of inflammatory exudations. It is the commonest cause of a retro- colic position of the appendix. Its presence, or the adhesions which it produces to the left of the caecum, may arrest the completion of caecal torsion (see figs. 2, 5,and 6).
  
spread of inflammatory exudations. It is the commonest cause of a retro-
 
colic position of the appendix. Its presence, or the adhesions which it
 
produces to the left of the caecum, may arrest the completion of caecal
 
torsion (see figs. 2, 5,and 6).
 
  
It may occasionally form the medial boundary of the retro-colic fossa.
+
* 1 “Morphology of the Digestive Tract,” by Byron Robinson, M.D., Joum. 0] Anat. and Phys., xxxiii. ‘
When the last part of the ileum and the corresponding part of the
 
mesentery adhere to the posterior abdominal wall, the adhesion forms the
 
  
  
 
  
 +
FIG. 6.  Foetus No. XIII.
  
FIG. 6. —Foetus No. XIII.
+
It may occasionally form the medial boundary of the retro-colic fossa. When the last part of the ileum and the corresponding part of the mesentery adhere to the posterior abdominal wall, the adhesion forms the left boundary of the retro—colic fossa, and the genito-mesenteric fold may liequite to the left of the fossa. It is possible that an inguinal hernia of the caecum and lower part of the ileum may in some cases be produced by the traction of the fold if it has been connected with the suspensory ligament of the testis during the passage of this organ to the scrotum. A further inquiry Will have to be made into its relations to the lymphatic vessels.
  
left boundary of the retro—colic fossa, and the genito-mesenteric fold may
 
liequite to the left of the fossa. It is possible that an inguinal hernia of
 
the caecum and lower part of the ileum may in some cases be produced by
 
the traction of the fold if it has been connected with the suspensory ligament
 
of the testis during the passage of this organ to the scrotum. A further
 
inquiry Will have to be made into its relations to the lymphatic Vessels.
 
  
We have already noted the presence in the fold of a large number of
+
We have already noted the presence in the fold of a large number of lymphatic glands; and the possibility that through it the lymphatic vessels of the genital gland in each sex, appendicular caecum, ileum, duodenum, and stomach, may be thrown into communication with one another has to be kept in mind. As I shall describe later, the fold may influence the form of the pelvic colon, and it may itself be modified by the bowel.
lymphatic glands; and the possibility that through it the lymphatic vessels
 
of the genital gland in each sex, appendicular caecum, ileum, duodenum, and
 
84 Studies of the Intestine and Peritoneum in the Human Foetus
 
  
stomach, may be thrown into communication with one another has to be
 
  
kept in mind. As I shall describe later, the fold may influence the form of
+
As for the fate of the genito-mesenteric fold? We have seen that the upper edge may persist as the free edge of the duodeno—renal ligament. Its lower part may persist in the adult, forming the medial boundary of the retro-colic fossa, or passing from the ileum or appendix. As has been noticed in the full—ti1ne foetus which was examined, part of the fold may disappear through the mesentery fusing down over it to the posterior abdominal wall. The remainder of the fold that part attached above to the mesentery along the line of the ileac branch of the ileo-colic artery) may partly disappear through fusion with the peritoneum of the posterior abdominal wall, owing perhaps to pressure exerted upon the left surface of the fold by the pelvic colon. This is clearly demonstrated in one foetus. In this foetus the summit of the primitive omega loop of pelvic colon had rotated downwards along an arc convex towards the right. One of the extremities of the arc is at the lower end of a small, still persistent part of the genito-mesenteric fold which passes downwards from the mesentery. The other is at the genital border of the suspensory ligament of the testis (see fig.
  
the pelvic colon, and it may itself be modified by the bowel.
 
  
As for the fate of the genito-mesenteric fold? We have seen that the
+
The genito-mesenteric fold and the plica vascularis (see fig. 4, C) lie each with its right surface turned and apposed to the posterior abdominal wall. 011 pushing up what has been the summit of the colon, it follows exactly the line of this are. The summit had glided downwards upon the left surface of the genito-mesenteric fold, pushing it, and with it the plica vascularis, over upon its right side. Moreover, it had caused, as a result of the pressure, the part of the genito-mesenteric fold with which it had come into contact to adhere by its right surface to the parietal peritoneum.
upper edge may persist as the free edge of the duodeno—renal ligament.
 
Its lower part may persist in the adult, forming the medial boundary of the
 
retro-colic fossa, or passing from the ileum or appendix. As has been noticed
 
in the full—ti1ne foetus which was examined, part of the fold may disappear
 
through the mesentery fusing down over it to the posterior abdominal wall.
 
The remainder of the fold  that part attached above to the mesentery
 
along the line of the ileac branch of the ileo-colic artery) may partly
 
disappear through fusion with the peritoneum of the posterior abdominal
 
wall, owing perhaps to pressure exerted upon the left surface of the fold by
 
the pelvic colon. This is clearly demonstrated in one foetus. In this foetus
 
the summit of the primitive omega loop of pelvic colon had rotated downwards along an arc convex towards the right. One of the extremities of
 
the arc is at the lower end of a small, still persistent part of the genito-mesenteric fold which passes downwards from the mesentery. The other is
 
at the genital border of the suspensory ligament of the testis (see fig.  
 
  
The genito-mesenteric fold and the plica vascularis (see fig. 4, C) lie
 
each with its right surface turned and apposed to the posterior abdominal
 
wall. 011 pushing up what has been the summit of the colon, it follows
 
exactly the line of this are. The summit had glided downwards upon the
 
left surface of the genito-mesenteric fold, pushing it, and with it the plica
 
vascularis, over upon its right side. Moreover, it had caused, as a result of
 
the pressure, the part of the genito-mesenteric fold with which it had come
 
into contact to adhere by its right surface to the parietal peritoneum.
 
  
Moreover, on exerting slight traction on the suspensory ligament, it is
+
Moreover, on exerting slight traction on the suspensory ligament, it is noted that the peritoneum upon the posterior abdominal wall is freely movable over an area between two lines (see fig. 4 (1) and (2) ). One of these leads upwards and to the right from the plica vascularis to the free edge of the persistent part of the genito—1nesenteric fold; and the other leads upwards from the plica vascularis, along the line of the spermatic vessels, as far as the root of the mesentery. These lines map out peritoneum which evidently has been derived from the genito-mesenteric fold.
noted that the peritoneum upon the posterior abdominal wall is freely
 
movable over an area between two lines (see fig. 4 (1) and (2) ). One of
 
these leads upwards and to the right from the plica vascularis to the free
 
edge of the persistent part of the genito—1nesenteric fold; and the other
 
leads upwards from the plica vascularis, along the line of the spermatic
 
vessels, as far as the root of the mesentery. These lines map out peritoneum
 
which evidently has been derived from the genito-mesenteric fold.
 
  
  
This only confirms the View that the fold had adhered to the posterior
+
This only confirms the View that the fold had adhered to the posterior abdominal wall; and it is apparent that the fold had not adhered as a result of a cause such as is expressed in the “displacement” theory, but the result of the soldering together of endothelial laminae.
abdominal wall; and it is apparent that the fold had not adhered as a
 
result of a cause such as is expressed in the “displacement” theory, but  
 
the result of the soldering together of endothelial laminae.
 
  
  

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Reid DG. Studies of the Intestine and Peritoneum in the Human Foetus: Part I. (1911) J Anat Physiol. 45(2): 73-84. PMID 17232876

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This 1913 paper is the first in this historical series describing human fetal intestine development. Note many of the terms introduced in this paper are historic terminology, no longer applied to describing the intestinal anatomy and some intestinal developmental concepts have been reviewed since this early series.



Other papers in this 6 part series by Douglas Reid:

  1. Reid DG. Studies of the Intestine and Peritoneum in the Human Foetus: Part I. (1911) J Anat Physiol. 45(2): 73-84. PMID 17232876
  2. Reid DG. Studies of the Intestine and Peritoneum in the Human Foetus: Part II. (1911) 45(4):406-15. PMID 17232897
  3. Reid DG. Studies of the Intestine and Peritoneum in the Human Foetus: Part III. (1912) 46(4):400-415. PMID17232936
  4. Reid DG. Studies of the Intestine and Peritoneum in the Human Foetus: Part IV. (1913) J Anat Physiol. 47(3): 255-267. PMID 17232956
  5. Reid DG. Studies of the Intestine and Peritoneum in the Human Foetus: Part V. (1913) J Anat Physiol. 47(3): 268-281. PMID 17232957
  6. Reid DG. Studies of the intestine and peritoneum in the human foetus: Part VI. (1913) J Anat Physiol. 47(4): 486-509. PMID 17232976


See also the historic paper Frazer JE. and Robbins RH. On the factors concerned in causing rotation of the intestine in man. (1915) J Anat Physiol. 50(1): 75-110. PMID 17233053
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1878 Alimentary Canal | 1882 The Organs of the Inner Germ-Layer The Alimentary Tube with its Appended Organs | 1884 Great omentum and transverse mesocolon | 1902 The Organs of Digestion | 1903 Submaxillary Gland | 1906 Liver | 1907 Development of the Digestive System | 1907 Atlas | 1907 23 Somite Embryo | 1908 Liver and Vascular | 1910 Mucous membrane Oesophagus to Small Intestine | 1910 Large intestine and Vermiform process | 1911-13 Intestine and Peritoneum - Part 1 | Part 2 | Part 3 | Part 5 | Part 6 | 1912 Digestive Tract | 1912 Stomach | 1914 Digestive Tract | 1914 Intestines | 1914 Rectum | 1915 Pharynx | 1915 Intestinal Rotation | 1917 Entodermal Canal | 1918 Anatomy | 1921 Alimentary Tube | 1932 Gall Bladder | 1939 Alimentary Canal Looping | 2008 Liver | 2016 GIT Notes | Historic Disclaimer
Human Embryo: 1908 13-14 Somite Embryo | 1921 Liver Suspensory Ligament | 1926 22 Somite Embryo | 1907 23 Somite Embryo | 1937 25 Somite Embryo | 1914 27 Somite Embryo | 1914 Week 7 Embryo
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Studies of the Intestine and Peritoneum in the Human Foetus. Part I

By Douglas G. Reid, M.B., Ch.B. Edin., B.A. Trin. Coll. Camb.,

Demonstrator of Anatomy in the University of Cambridge.


These studies are based chiefly on the examination of the arrangement of the peritoneum in twenty fetuses in the Cambridge Museum (of which nine were female specimens), varying in length from 12 to 20 cms. (vertex-coccygeal measurement).


In this part I shall describe a peritoneal fold present in eleven (six males and five females) of the twenty foetuses (55 per cent.). Moreover, there is evidence of its having been present at an earlier stage in at least three others. In order to understand the changes accompanying the presence of this fold, it is necessary to refer to the line of the root of the foetal mesentery. Except in the case of the part fixed to the front of the fourth portion (ascending part of the pars inferior) of the duodenum, the root of the mesentery is attached along a line which is still practically transverse. It is implanted upon the whole of the front of the third portion (transverse part of the pars inferior) of the duodenum, and to the right of this upon the peritoneum covering ‘the front of the right kidney. It to be noted that the root is attached to the posterior abdominal wall exactly along the line of the ileo—colic artery which arises from the superior mesenteric at (never below) the place where this artery crosses the third portion of the duodenum, and courses towards the right. At this stage the surfaces of the mesentery may be described as being superior and inferior. Indeed, the mesentery lies often horizontally for some distance from its root, forming a shelf, supported on its inferior surface by the large intra-abdominally placed pelvic colon. One notes here that the retro—colic fossa in the adult is limited medially by a fold, the 1nesenterico—iliac fold of Jonnesco (plica genito-enterica of Treitz). This is described as being merely the insertion of the mesentery in the iliac fossa, where it has a very variable line of insertion, in the female being continuous (always?) with the broad ligament. The special genito-mesenteric fold (see fig. 1) which I now describe passes downwards from the inferior surface of the mesentery in the right half of the abdomen.


There is nothing corresponding to it on the left side. It forms an antero—posterior septum lying in the vertical plane, incompletely subdividing the portion of the abdominal cavity below the root of the mesentery into two compartments. The smaller of these is to its right side, and contains the caecum; the larger is to its left side, and contains the pelvic colon. The fold is, as it were,.propped up on the sides by these portions of the bowel.


FIG. 1. Foetus No. XI.


The fold is triangular in form. It presents right and left surfaces, both of which are generally free. Of its borders, two are attached: one, the posterior, to the posterior abdominal wall along the line of the right spermatic or ovarian vessels; and the other, the superior or mesenteric, to the inferior surface of the mesentery, often to a considerable extent.


The ileac branch of the ileo-colic artery leaves the fold, in which it lies at the root of the mesentery (to be described later), and courses forwards, away from the posterior abdominal wall, in the substance of the mesentery.


FIG. 2. Foetus No. XIV.

The attachment of the genito-mesenteric fold to the mesentery is generally exactly along the line of this artery. The anterior border of the fold is in most cases free. It is usually continuous below with the suspensory ligament of the ovary, and its inferior extremity appears in consequence truncated. This fold is not to be confounded with a mere dihedral angling of the mesentery, in relation to the ileac branch of the ileo-colic artery, although in some instances the ileum may become adherent to its right side. This adhesion may occur close to the ovary, which thus comes (as in one foetus) to be intimately bound to the ileum. The uniting band here is evidently not a pathological adhesion. However, the continuity of the fold with the suspensory ligament of the ovary is not constant; the two folds may be separate, although lying in line one above the other.


In the male foetuses the fold is not usually continued into the suspensory ligament of the testis—although it may reach to this—saVe through the prominence produced by the spermatic vessels descending behind the peritoneum of the posterior abdominal wall.


In the full-time foetus (fig. 3), in which the genito-mesenteric fold is present, the parts have acquired almost the position which they occupy in the adult, the caecum lying in the right iliac fossa, and the hepatic and splenic flexures in their usual adult position. But the whole of the ascending and transverse colon is free of attachment to the posterior abdominal wall, as is the 1nesentery of the ascending colon, jejunum, and ileum. All ca11 be pulled freely forward. In other words, almost the whole of the peritoneum of the intestinal loop is free. The caecuin having completed its descent, the ileo-colic vessels new take a definitely descending course, in the free peritoneum of the loop, towards the ileo-czecal junction. They lie in the obvious folds of peritoneum, along the line of which the root of the mesentery is usually attached. Had the peritoneum of the intestinal loop become soldered down at these folds, the line of the root of the mesentery would have followed exactly the direction usually taken in the adult. It is true that the root of the mesentery passes down upon the fourth portion of the duodenum; but this is the primitive condition, this part of the duodenum belonging to the intestinal, and not to the duodenal loop. The anterior surfaces of the first, second, and third portions of the duodenum are free (5.0. the peritoneum of the intestinal loop and the transverse colon can be pulled forwards off these parts). The first and second parts of the duodenum are also free behind, as is the posterior surface of the meso—duodenum and the head of the pancreas. But although the peritoneum of the intestinal loop, save where it covers the front of the meso—duodenum, is free of adhesion, on lifting the loop forwards the large triangular genito-mesenteric fold is seen passing from the posterior surface of its peritoneum backwards to the posterior abdominal wall.


The whole appearance is one of a remarkable T—shaped mesentery holding down the intestine, and taking the place of the normal root of the mesentery.


The fold extends downwards to the posterior (internal) abdominal ring. The mesenteric border is attached to the duodenum at the angle between the second and third portions——and it is here that the duodenum descends lowest in the abdomen—as well as to the peritoneum of the intestinal loop along a line 3.8 cms. long.


This line lies to the right of the ileo-colic artery above, but lower down it passes directly along the ileac branch of this vessel, as in the other foetuses. The fold, therefore, would have become reduced in size if the intestinal loop and its peritoneum had become soldered down to the normal extent. The part of the fold related to the ileac branch, along which adhesion does not occur, would, however, have remained.


FIG. 3. Drawn with careful measureliients from a full-time fmtus. two-thirds actual size. Viewed from the right side. The artery is -.1 branch of the right gastro-epiploic (not figured).


Its posterior border, from the duodenum downwards to the internal abdominal ring, is 6.4: cms. long. The anterior, or free, border measures 7.5 cms. in length. The mesenteric border lies an average distance of 2 cms. from the ascending colon, and a large number of lacteal glands lie in the mesentery along the ileac artery. The surfaces of the fold are free, and between their endothelial laminae are many lymphatic glands and a network of blood-vessels, visible to the naked eye. The portion of the great omentum to the right of the pylorus (ac. the right process of the great omentum) extends downwards upon the colon as far as the root of the appendicular caecum. A branch of the right gastro—epiploic artery, lying in this, extends upon the colon to the hepatic flexure (see fig. It then leaves the great omentum and passes over the posterior surface of the upper part of the ascending colon and comes to lie in the mesocolon. Leaving this, it crosses the lower part of the second portion of the duodenum, and gets on to the posterior abdominal Wall, to the right side of the fold. After a curved course, it enters the genito-mesenteric fold at its posterior border, and finally emerging from the fold at its mesenteric border, again enters the mesentery, and ends on the colon near the caecum. The spermatic vessels lie along the parietal attachment of the fold. Although the second portion of the duodenum is free behind, a thin sheet of peritoneum (see fig. 3) passes from its right border to the front of the right kidney. This sheet lies in a vertical and antero-posterior plane, and its right endothelial lamina is continuous with the corresponding lamina of the genito-mesenteric fold. A s As will be seen from the foregoing description of the duodenum, it forms the right boundary of a large retro—duodenal fossa, which opens above at the foramen of Winslow into the general peritoneal cavity. It presents at the level of the junction of the first and second portions of the duodenum a superior free horizontal edge stretching from the duodenum to the kidney. The upper part of this sheet, therefore, is simply the duodeno-renal ligament.


The vessels ramifying upon the anterior surface of the second portion of the duodenum are not so distinctly visible as those seen upon the front of the first portion. This is due to the presence of a peritoneal veil which passes from the posterior surface of the peritoneum of the intestinal loop over the front of the second part of the duodenum, to be continuous with the peritoneal sheet, which anchors the right border of the duodenum to the kidney. This veil is also continuous below, like the sheet itself, with the right endothelial lamina of the genito-mesenteric fold.


Certain modifications were found in the line of attachment of the mesentery in foetuses in which the genito-mesenteric fold is present, as well as some examples of visceral adhesions to the fold.


Without an actual alteration in the line of the root of the mesentery occurring, a deep fossa is present in one foetus on the upper surface of the F mesentery, the bottom of the fossa corresponding to the line of attachment of the genito-mesenteric fold.


In two foetuses the ileo-colic artery to the right of the duodenum forms the base of a triangle, the apex of which is below, and the sides of which are placed at the root of the mesentery. The genito-mesenteric fold is attached to the mesentery opposite the apex (73.6. opposite the most depressed part of the mesenteric root).


Again, in two others, although the root of the mesentery retains its intimate relation to the ileo-colic artery to the left side of the fold, the ileum, in the last 1'5 cms. and 2 cms. of its course, adheres firmly, along with the whole of its mesentery, to the peritoneum of the posterior abdominal wall to its right side, and the ileum also adheres to the right surface of the fold itself. In one of these foetuses the mesentery indeed is also tacked down slightly to the abdominal Wall on the left side of the fold. In this foetus the ileac artery is placed in a fold of peritoneum, J quite 3 mms. high, Which is seen projecting from the upper surface of the mesentery. This arterial fold, since it lies over the genito-mesenteric fold, owes its existence to this tacking down of the mesentery on both sides. It forms a veritable septum, subdividing the marked fossa resulting from this depression of both laminae of the mesentery into a right and left part. In these, and in another foetus, the ileum adheres definitely to the right side of the genito-mesenteric fold, whose connection with the mesentery is still distinctly seen.


  • 1 For a good figure of this see Spalteholz’s Atlas.


"In two other foetuses the genito-mesenteric fold passes from the non-mesenteric border of the terminal portion of the ileum, and has no apparent connection with the mesentery.


But, in the light of all the other instances, there is little doubt that in these cases the ileum had first of all adhered by one of its aspects to the right side of the fold. Through great solidity of soldering of the peritoneal surfaces together, this surface of the ileum became again apparently free.


I have seen a comparably great solidity of fusion in the case of the great omentum, which on this account may appear, even before birth, to have partially disappeared. It may be seen also in the case of the appendix.


Thus in one foetus the genito-mesenteric fold passes from the usually free border of the appendix, and does not appear to be continued over the appendix to the mesentery.


The appendix is connected to the mesentery by a sheet of peritoneum (see fig. 4:, A), which at first sight appeared to be simply meso-appendix. But the clue to its real nature is found in the fact that, when viewed from the left (see fig. 4), the artery of the appendicular caecum (Which occupies a distinct fold along the free edge of the meso-appendix) seems suddenly to disappear, becoming suddenly obscured by a peritoneal veil. But when viewed from the right the artery is distinctly visible to the usual extent. The front edge of this veil is continued into the free edge of a sheet of peritoneum above the artery, and thereby passes to the inferior surface of the mesentery. These appearances leave no doubt that not only had the serous coat of the appendix adhered to the right side of the genito-mesenteric fold, a condition seen in another foetus, but that one surface of the meso-appendix, from border to border, had also similarly adhered. Here again the appendix, save at its borders, appears free of the fold; and the explanation of this condition appears to be that it results from solidity of soldering.


A similar arrangement in connection with the appendix and meso-appendix was found in an adult male. Here a slight fold passed downwards upon the external iliac vessels from the usually free border of the appendix. The fold, then, which connected the appendix to the mesentery in these cases is the result of the fusion together of two sheets of peritoneum, and represents genito-mesenteric fold on the left and meso—appendix on the right.



FIG. 4. Fcetus No. X.


We have seen that, in association with the genito-mesenteric fold, the ileum and its mesentery may become adherent to the posterior abdominal wall on the right side of the fold. Similarly, the caecum may become adherent to the posterior abdominal wall on this side. Thus, in one foetus the caecum, its appendix, and the meso-appendix, and with it the “blood-less ” fold of Treves, are firmly soldered down to the abdominal wall on the right side of the genito-mesenteric fold ; and the “ bloodless fold ” was similarly seen directly adherent to the posterior abdominal wall in associa- tion with this fold. It is essentially on the right of the fold, as well as actually to the right surface of the fold itself, that these adhesions occur.


In only three cases is the genito-mesenteric fold associated with a retro-colic fossa. But in most of the foetuses in which it is present the appendix is definitely retro-colic.


The genito-mesenteric fold appears to be late in making its appearance, if one can. judge from its absence in a 25-mm. foetus (given to me by Mr John Griffith, B.-A., of Christ’s College). a How this fold is produced is not clear. It is possible that sometimes the right extremity of the great omentum (which is late in appearing) may assist in forming it, perhaps extending in some cases off the colon on to the posterior abdominal wall, and fusing, as it does so, with the right surface of the fold. The presence of the branch of the right gastro-epiploic artery in the fold—and indeed projecting, rather from’ its right surface, as if it had been added on—-and behind the peritoneum of the posterior abdominal wall might thus be explained. It is difficult to see why its mesenteric border should be related to the ileac branch of the ileo-colic artery?


The fold may exercise considerable influence on parts about it. It is significant that the lowest point of the duodenum is at the place of attachment of this fold. This suggests that it exerts a traction upon the duodenum at this part. If this traction be excessive, it may be a cause of downward displacement of the duodenum.


The second part of the duodenum may also adhere to the left side of the fold.


The duodeno-renal sheet and veil of peritoneum already described were formed by the upper part of the genito-mesenteric fold. We may also infer from this foetus that the duodeno-renal ligament of Huschke is practically the upper part of the fold.


In the light of these specimens, and associated with the elongation of the ascending colon and the descent of the genital gland, this fold is evidently a cause of depression and actual tacking down of the mesentery, with a consequent lowering of the mesenteric root, with which the ileo-colic artery may retain or lose, to a greater.or less degree, its close relation.


The fold may also assist in producing adhesion of the duodenum, caecum, and ileum to the posterior abdominal Wall. Adhesion in the adult binding down the terminal part of the ileum, the caecum, the appendix, the mesentery, the meso—appendix, and even the “bloodless” fold of Treves, need not be the result of pathological changes, unless the natural cause We have indicated for the adhesion can be excluded, although a genito-mesenteric fold may not always be seen even in the foetus.

The ovary may be bound, sometimes very intimately, to the ileum or appendix, through the adhesion of these parts of the bowel to the right surface of the fold.



FIG. 5. Foetus No. XVIII. Part of the side wall of the abdomen has been removed.


There is no general shifting of the endothelial layers in such a manner that What was once free peritoneal surface remains free, apparently produced by the genito-mesenteric fold in determining these adhesions.


Its action upon the mesentery is to render a part of it. more immobile ; and through it, apparently, a traction is exerted upon the mesentery.

The genito-mesenteric fold must be of considerable interest from a surgical and gynaecological point of view. Its adhesion may restrict the spread of inflammatory exudations. It is the commonest cause of a retro- colic position of the appendix. Its presence, or the adhesions which it produces to the left of the caecum, may arrest the completion of caecal torsion (see figs. 2, 5,and 6).


  • 1 “Morphology of the Digestive Tract,” by Byron Robinson, M.D., Joum. 0] Anat. and Phys., xxxiii. ‘


FIG. 6. Foetus No. XIII.

It may occasionally form the medial boundary of the retro-colic fossa. When the last part of the ileum and the corresponding part of the mesentery adhere to the posterior abdominal wall, the adhesion forms the left boundary of the retro—colic fossa, and the genito-mesenteric fold may liequite to the left of the fossa. It is possible that an inguinal hernia of the caecum and lower part of the ileum may in some cases be produced by the traction of the fold if it has been connected with the suspensory ligament of the testis during the passage of this organ to the scrotum. A further inquiry Will have to be made into its relations to the lymphatic vessels.


We have already noted the presence in the fold of a large number of lymphatic glands; and the possibility that through it the lymphatic vessels of the genital gland in each sex, appendicular caecum, ileum, duodenum, and stomach, may be thrown into communication with one another has to be kept in mind. As I shall describe later, the fold may influence the form of the pelvic colon, and it may itself be modified by the bowel.


As for the fate of the genito-mesenteric fold? We have seen that the upper edge may persist as the free edge of the duodeno—renal ligament. Its lower part may persist in the adult, forming the medial boundary of the retro-colic fossa, or passing from the ileum or appendix. As has been noticed in the full—ti1ne foetus which was examined, part of the fold may disappear through the mesentery fusing down over it to the posterior abdominal wall. The remainder of the fold that part attached above to the mesentery along the line of the ileac branch of the ileo-colic artery) may partly disappear through fusion with the peritoneum of the posterior abdominal wall, owing perhaps to pressure exerted upon the left surface of the fold by the pelvic colon. This is clearly demonstrated in one foetus. In this foetus the summit of the primitive omega loop of pelvic colon had rotated downwards along an arc convex towards the right. One of the extremities of the arc is at the lower end of a small, still persistent part of the genito-mesenteric fold which passes downwards from the mesentery. The other is at the genital border of the suspensory ligament of the testis (see fig.


The genito-mesenteric fold and the plica vascularis (see fig. 4, C) lie each with its right surface turned and apposed to the posterior abdominal wall. 011 pushing up what has been the summit of the colon, it follows exactly the line of this are. The summit had glided downwards upon the left surface of the genito-mesenteric fold, pushing it, and with it the plica vascularis, over upon its right side. Moreover, it had caused, as a result of the pressure, the part of the genito-mesenteric fold with which it had come into contact to adhere by its right surface to the parietal peritoneum.


Moreover, on exerting slight traction on the suspensory ligament, it is noted that the peritoneum upon the posterior abdominal wall is freely movable over an area between two lines (see fig. 4 (1) and (2) ). One of these leads upwards and to the right from the plica vascularis to the free edge of the persistent part of the genito—1nesenteric fold; and the other leads upwards from the plica vascularis, along the line of the spermatic vessels, as far as the root of the mesentery. These lines map out peritoneum which evidently has been derived from the genito-mesenteric fold.


This only confirms the View that the fold had adhered to the posterior abdominal wall; and it is apparent that the fold had not adhered as a result of a cause such as is expressed in the “displacement” theory, but the result of the soldering together of endothelial laminae.


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Cite this page: Hill, M.A. (2019, October 18) Embryology Paper - Studies of the intestine and peritoneum in the human foetus - part 1. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_Studies_of_the_intestine_and_peritoneum_in_the_human_foetus_-_part_1

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