9.23.96
Dr.Orsini

Meg setting up mock practical Thurs PM/Fri AM. Computer program should be 
up and running by Monday.

Dr. Dodson will discuss mesentery in the next unit. But, for now, a brief 
overview:

diagram of early embryo highlighting primitive gut tube and expansion of 
foregut into stomach.

In development, there is a thin dorsal attachment from the gut tube to 
the dorsum, which is considered a mesentery, and there is also a ventral 
mesentery which is OPEN - eg, not continuous over ventral body wall.

Liver grows from gut tube between stomach and ventral mesentery, and as 
it grows presses into the ventral mesentery while keeping its connection 
to the gut tube (bile duct) - so, it's developing into the ventral 
mesentery. Note also that the peritoneal membrane is divided into 
parietal and visceral, similar to the pleural membranes of the thorax. 
[see diagram of cross section]

[diagram of more mature embryo] note ventral mesenteric remnant below 
liver is called falciform ligament, and the free edge of that is the 
round ligament of the liver.

in adult, the former dorsal mesentery is the greater omentum, and the 
former ventral mesentery is the lesser omentum. Note that within the two 
layers of omentum are some vessels running to the stomach. When you look 
at the greater oomentum grossly, they talk about th two layers- 
superficial leaf and deep leaf. the omental bursa is the "space" between 
the superficial and deep leaves, which really isn't normally present 
'cause the leaves are smushed against each other.

When you look at pancreas in lab, will see two pancreatic ducts....make 
sure to open duodenum and scrape away mucosa. First bump is major 
duodenal papilla, and the bile and pancreatic ducts enter there. 2-3 cm 
caudal to that papilla in the dog there may be another pancreatic duct.