230 NORMAL HISTOLOGY. 



nant uterus. The bloodvessels also enlarge and acquire thicker 

 walls. These retain much of this increase of size, even after the 

 involution of the uterus following parturition, but the muscular 

 fibres suffer a partial fatty degeneration, which restores them to 

 nearly their original condition. 



4. The Vagina (Fig. 207). — The subepithelial fibrous coat of the 

 vagina is covered with small papillae, which project into the epithe- 



Fig. 207. 



Portion of a longitudinal section of the vaginal wall. (Benda and Guenther's Atlas.) a, 

 stratified epithelium ; 6, subepithelial areolar tissue ; c, muscularis mucosae ; d, areolar 

 submucosa containing vascular trunks ; e, muscular coat. Outside of the latter is the 

 ill-defined fibrous coat, not represented in the figure. 



Hum. Outside of this coat is one of smooth muscular tissue, which 

 is not clearly divisible into layers, but in which the inner fibres are 

 chiefly circular, forming an imperfectly defined muscularis mucosa?, 

 while the outer have a longitudinal direction, and may be regarded 

 as the true muscular coat of the vagina. Outside of the muscular 

 coat is a layer of areolar tissue connecting the vagina with the 

 neighboring parts, except at its posterior and upper part, where it 

 is covered with a serous membrane, forming part of the peritoneum. 

 5. The External Genitals. — The hymen is a fold of the mucous 

 membrane, and consists of fibrous tissue with a covering of strati- 

 fied epithelium. The same general structure obtains also in the labia 



