Till-: REPRODUCTIVE ORGANS. 



213 



substance, in which fibres can be distinguished only with difficulty. 

 The surface of the mucous membrane is covered with a layer of 

 ciliated columnar epithelium, which is continued into long tub- 

 ular glands penetrating the superficial portions of the muscularis 

 mucosae, where they frequently branch before terminating in blind 

 extremities. It should be borne in mind that at the extremities of 

 these glands the whole tubule is often filled with epithelial cells, so 

 that no lumen is visible. In their course into the mucous mem- 

 brane these glands are usually straight at first, but in their deeper 

 portions become tortuous (Figs. 190 and 191). 



FIG. 190. 



Section through the uterine wall of a rabbit , near one of the cornua. (Schtiffer.) m, gland- 

 ular portion of the mucous membrane ; m, m, muscularis mucosse ; a, submucosa of are- 

 olar tissue, containing the large bloodvessels which send branches into the stroma of the 

 mucous membrane; cm, circular layer of the muscular coat; lm, longitudinal, thicker 

 layer of the muscular coat ; s, serous coat, derived from a reflection of the peritoneum. 



During the childbearing period of life the portion of the mucous 

 membrane resting upon the muscularis mucosse is the seat of active 

 changes which pass through a cycle corresponding to each men- 

 strual period, but interrupted by a special series of changes during 



