1. Development of the peritoneum Surgical anatomy of the omental bursa
Ágnes Nemeskéri
April 2014
Semmelweis University
Department of Human Morphology and Developmental
Biology

2. Peritoneum develops from…
develops from the mesoderm of the trilaminar embryo
the lateral plate mesoderm splits to form two layers separated by an intraembryonic coelom 
the two layers develop later into the visceral and parietal layers found in all serous cavities, including the peritoneum
Symmetric!!!!
-from the specific part of intraembryonic coelom:
from the distal part of pericardio-peritoneal canal
from the somato- and splanchnopleura of the distal part of foregut, midgut, hindgut

3. Coelomic epithelium
-initially it is a pseudostratified germinal layer (later single squamous cell layer) from which cellular progeny with different fates arise in specific sites and at specific developmental times
- proliferative splanchnopleuric epithelium produces:
cell populations for the mucosa and muscularis of the gut (except epithelium of gut)
interstitial Cajal cells – pacemaker cells of the intestines
lamina propria and epithelium of visceral peritoneum (the serosa of the gut wall)
- proliferative somatopleuric epithelium gives rise:
lamina propria and epithelium of the parietal peritoneum
Cells Derived from the Coelomic Epithelium Contribute
to Multiple Gastrointestinal Tissues in Mouse Embryos
Rita Carmona1, Elena Cano1, Andrea Mattiotti1, Joaquı´n Gaztambide2, Ramo´n Mun˜oz-Cha´puli

4. Mesenteries Symmetric!! Gut grows…..
- splanchnic mesenchyme accumulates around the endodermal epithelium
regions where the medial portions of the intraembryonic coelom come together are termed:
mesentery
is the splanchnic mesoderm that connects the primitive gut to the body wall
- composed of two layers of peritoneum with intervening mesenchyme
- contain the neurovascular structures which pass to and from the gut
Symmetric!!

5. Asymmetric!!
Integration of Left-Right Pitx2 Transcription and Wnt Signaling Drives Asymmetric Gut Morphogenesis via Daam2
Ian C. Welsh,1 Michael Thomsen,1 David W. Gludish,1 Catalina Alfonso-Parra,1 Yan Bai,2 James F. Martin,2 and Natasza A. Kurpios1,*
A critical aspect of gut morphogenesis is initiation of a leftward tilt, and failure to do so leads to gut malrotation and volvulus
- the direction of tilt is specified by asymmetric cell behaviors within the dorsal mesentery (DM)
Pitx2, the key transcription factor responsible for the transfer of left-right (L-R) information from early gastrulation to morphogenesis
Pitx2 is a master regulator of L-R organ development
cellular targets that drive asymmetric morphogenesis are not known

6. 6th gestational week Derivatives of foregut: Derivatives of midgut:
1. primordial pharynx
2. lower respiratory system
3. esophagus
4. stomach
5. duodenum above the inlet of common bile duct
6. liver, biliary structures
7. pancreas
Derivatives of midgut:
1. duodenum caudal portion
2. ileum, jejunum
3. cecum, ascending colon, transverse colon right half
Derivatives of hindgut:
1. transverse colon left half
2. descending colon, sigmoid colon, rectum, anal canal (sup)
3. urinary bladder, urethra 2/3

7. Ventral and dorsal mesenteries
mesogastrium
dorsal
ventral
- caudal portion of the foregut enlarges
- differential growth of the walls of the stomach (dorsally grows faster)
- 90º- „rotation” to the right
- cranial end to the left
- caudal end to the right and up
right pleuroperitoneal canal forms a discrete region of peritoneal cavity:
the lesser sac
remaining left pleuroperitoneal canal and remainder of peritoneal cavity form:
the greater sac 
entrance to the original right pleuroperitoneal canal (lesser sac) becomes reduced in size
the epiploic foramen
aditus of the omental bursa

8. Ventral and dorsal mesogastrium
pancreas
falciform
ligament
dorsal
mesogastrium
stomach rotates around its axis
growth of the liver and particularly of the vessels and ducts which enter and leave the liver
these developments permit stomach expansion both anteriorly and posteriorly 

9. b) forms fusiform structure
Stomach Development
a) week 4 - forgut inferior to transverse septum proliferates (expands).
b) forms fusiform structure
c) week 5 - dorsal wall grows rapidly (greater curvature).
d) bends tube ventrally (90 degrees)
e) week 7 and 8 - dorsal mesentery growth
f) rotates stomach laterally (90 degrees) greater curvature to left, lesser curvature to right

11. Dorsal mesogastrium and mesoduodenum
Pancreatic primordium starts to grow into the dorsal mesoduodenum
Cranially into the dorsal mesogastrium
pancreas
spleen
stomach - duodenum
lesser omentum
adrenal gland
omental bursa
dorsal mesogastrium
- dorsally facing posterior layer of mesogastrium
fuses with the parietal covering of coelomic cavity
then degenerates
pancreas becomes retroperitoneal

12. Development of omental bursa
cavitation
n. vagus
-the attachment dorsal mesentery of the stomach rotating to the right will get to the left meanwile it elongates → omental bursa

13. I. „Rotation” of the midgut loop
I. „Rotation” of the midgut loop
cranial limb and : 90º „ rotates ” to the right (caudal limb to the left)
- during rotation, the cranial limb elongates and forms loops
2. caudal limb: 180 º „rotation” to the right
- shows little change: cecal swelling
cranial limb
umbilical cord
physiologic
umbilical
herniation
caudal limb
cecal diverticulum
6. week – midgut loop in sagittal plane
9. week – midgut loop: in a horizontal plane
„rotation” – not rotatory movement!!! – the small intestine becomes much longer than the body length,
passive realignment

14. II. „Rotation” of the midgut loop of intestine
10th week: the intestines return to the abdomen (enlargement of abdominal cavity??)
-small intestines from the cranial limb return first – posterior to the SMA
- as the large intestine returns: it undergoes a further 180° counterclockwise rotation

15. Fixation of the intestines
Rotation of the stomach and duodenum
duodenum and pancreas – to the right
Enlarged colon presses the duodenum and pancreas against the posterior abdominal wall
most of the duodenal mesentery is absorbed
duodenum has no mesentery
RETROPERITONEAL
Attachment of dorsal mesentery to the posterior abdominal wall
greatly modified after intestines return to the abdominal cavity
Dorsal mesentery originally is in the median plane
- intestines lengthen and their mesenteries are pressed against the posterior abdominal wall
- mesentery of ascending colon fuses with the parietal peritoneum and disappears
RETROPERITONEAL
- jejunum and ileum retain their mesenteries
- new line of attachment between the duodenojejunal junction and ileocecal junction

16. Surgical anatomy of omental bursa

17. Omental bursa

19. *Mesorectum – embryologic origin – the mesorectal fascia surrounds it
-metastasis in the mesorectum??
-did the tumor break throughthe mesorectal fascia??
2. mesorectal fascia derived from visceral peritoneum
1.Fascia praecascralis
-derived from parietalis peritoneum
-presacral veins!!!
*Mesorectum – embryologic origin – the mesorectal fascia surrounds it
-rectal aa. vv.
-lymph nodes and vessels
- inf. hypogastric plexus
-fatty connective tissue – around the rectum and upper part of anal canal
-down to the puborectal muscle

20. Malformation of the peritoneum
Agenesia of the greater omentum and complex anomaly of the peritoneum together with multiple malformations of the heart
-a very large ligament between stomach and transverse colon replaced the gastro-colic ligament and continued upwards as a mesocolon, while the omentum was entirely wanting. On the basis of Toldt's commonly accepted doctrine, the malformation may be interpreted as the expression of an agenesia of the bursa omentalis, of an incomplete fusion between primitive mesocolon and wall of the bursa omentalis, and of an excessive growth of the primitive mesocolon. (

21. Omentectomy partially or completely removed
performed on patients suffering from certain types of cancer
in extremely obese patients
Women comprise a large of number of omentectomy patients - cancer of ovary
cancer cells from the ovaries can spread to the surrounding omentum, the fatty tissue removed
In men, intestinal cancer is the main reason for needing an omentectomy
length and size of the small and large intestines can affect a large area of the omentum, significantly increasing the risk of the cancer spreading

22. Surgical approach to the pancreas

23. References