VAGINA. 311 



The yolk sac may be found with almost every placenta, as a very small cyst 

 adherent to the amnion in the placental area. If the distal end of the cord is 

 gently stretched a wing-like fold appears (Fig. 356), differing from all others by 

 containing no large vessels; the fold indicates the direction of the yolk sac which 

 may be exposed by stripping the amnion from the chorion. It may be beyond 

 the limits of the placenta. 



A mniotic villi are irregular, flat, opaque spots on the amnion near the distal 

 end of the cord. They are often present and may suggest a diseased condition. 

 As seen in Fig. 357 they are areas of imperfectly developed skin; since epithelial 

 elevations occur abundantly over the cords of certain mammals, these structures 

 of unknown significance are probably normal. 



VAGINA AND EXTERNAL GENITAL ORGANS. 



The vagina consists of a mucosa, (submucosa), muscularis and fibrosa. 

 Its epithelium is thick and stratified, its outer cells being squamous and 

 easily detached. It rests upon the papillae of the tunica propria, and 

 is thrown into coarse folds or rugae. Glands are absent. The tunica 

 propria is a delicate connective tissue with few elastic fibers, containing 

 a variable number of leucocytes. Occasionally there are solitary nodules, 

 above which numerous leucocytes wander into the epithelium. The sub- 

 mucosa consists of strong elastic and looser white fibers. The muscu- 

 laris includes an inner circular and a small outer longitudinal layer of 

 smooth muscle. The fibrosa is a firm connective tissue, well supplied 

 with elastic elements. Blood and lymphatic vessels are found in the 

 connective tissue layers, and wide veins form a close network between the 

 muscle bundles. There is a ganglionated plexus of nerves in the fibrosa. 



The mucous membrane of the vestibule differs from that of the vagina 

 in possessing glands. The numerous lesser vestibular glands, 0.5-3 mm - ' m 

 diameter, produce mucus; they occur chiefly near the clitoris and the 

 outlet of the urethra. The pair of large vestibular glands [Bartholin's] 

 also produce mucus; they correspond with the bulbourethral glands in 

 the male and are of similar structure. The hymen consists of fine fibered, 

 vascular connective tissue covered with mucous membrane. The clitoris 

 is a somewhat erectile body, resembling the penis. It includes two small 

 corpora cavernosa. The glans clitoridis contains a thick net of veins. 

 It is not, as in the male, at the tip of a corpus cavernosum urethrae which 

 begins as a median bulb in the perineal region; the bulbus in the female 

 exists as a pair of highly vascular bodies, one on either side of the vesti- 

 bule. Each is called a bulbus vestibuli. The labia minora contain seba- 

 ceous glands, 0.2-2.0 mm. in size, which are not connected with hair 

 follicles; they first become distinct between the third and sixth years. 

 The labia majora have the structure of skin. 



