280 ANATOMICAL TECHNOLOGY. 



"brane covering one side of a blood vessel. A similar membrane 

 will remain on the opposite side. 



§ 727. Omentum majus, epiploon, az. — Qavl (§ 716). — The epi- 

 ploon is a double walled sac formed by a duplication of a do'id)le 

 fold of peritoneum. The cavity of this sac is sometimes called the 

 lesser peritoneal camty. Demonstrate the sac-like character of the 

 omentum by tearing it open and divaricating the two walls. Dem- 

 onstrate that each waU of the sac is composed of two layers, as with 

 the mesentery, by tearing away one layer with the tracer. This 

 may be most easUy and satisfactorily done over a blood vessel or a 

 strip of fat. 



It will be seen from the above that the omental sac as it lies 

 collapsed on the intestines consists of four thicknesses of perito- 

 neum. 



§ 728. Foramen Winslovii, az. — ^Foramen of Winslow. — This is 

 the contracted mouth of the omental sac through which it communi- 

 cates with the general peritoneal cavity. It is relatively larger than 

 in man, and may be easily demonstrated by tearing open the sac 

 near the pylorus, lifting the two walls slightly and divaricating 

 them. There will be seen within the sac a small lobe of the liver 

 {lohus Spigelii), and at the caudal margin of this lobe, sometimes 

 partly filled by it, will be seen the foramen. It is about 2 cm. in 

 diameter, and is on the dorsal side of the ductus communis chole- 

 docTius and Vena porta. The foramen may likewise be demon- 

 strated by turning the duodenum to the left and finding the ductus 

 choledochus and Vena portge. This should be done in a perfectly 

 fresh and uninjured specimen, and the omental sac inflated by 

 blowing into the foramen with a bent glass tube or a large flexible 

 blow-pipe. 



§ 729. The Obvious Btrvcture of the peritoneum is like that of serous membranes gen- 

 erally — thin and transparent, smooth and glistening. 



§ 730. Microscopic Structure. — (A) Ectal layer of a single thickness of flattened nu- 

 cleated cells. (B) Attached or ental layer of connective tissue containing elastic and 

 white connective tissue fibers. Consult Frey, A ; Quain, A, II, 197 ; Strieker, A, 509. 



§ 731. GlEindulse Mesentericae, az. — Mesenteric glands. — The 

 SO called mesenteric glands belong to the lymphatic system. They 

 are between the layers of mesentery, and are especially large near 

 the caecum, some of them being 1-2 cm. thick and 3 cm. long. 



