382 THE ORGANS 



but is folded transverseh', forming the so-called rugce. Most au- 

 thorities agree that glands are wanting in the vagina, the mucus 

 found there being derived from the glands of the cervix. 



Blood-vessels. — The larger blood-vessels run in the submucosa, 

 giving off branches which break up into capillary networks in the sub- 

 mucosa, muscularis, and stroma. The vascular networks have a 

 general direction parallel to the surface. The capillaries empty into 

 veins which form a plexus of broad venous channels in the muscularis. 



The Lymphatics. — These follow in general the distribution of the 

 blood-vessels. 



Nerves. — Nerve fibres from both cerebro-spinal and sympathetic 

 ■ systems are found in the vagina. IMedullated (sensory) fibres, the 

 dendrites of spinal ganglion cells, form plexuses in the mucosa, from 

 which are given off delicate non-medullated terminals to the epithe- 

 lial cells. Non-medullated sympathetic fibres supply the muscularis 

 and the muscle of the vessel walls. Along these nerves are small 

 sympathetic ganglia. 



In the vestibule the epithelium gradually takes on the structure of 

 epidermis. Here are located small mucous glands — glandulce vestib- 

 ulares minores — especially numerous around the clitoris and opening 

 of the urethra. Larger mucous glands — glandulce vestibulares ma- 

 jores, or glands of Bartholin — analogous to Cowper's glands in the 

 male, are also found in the walls of the vestibule. 



The clitoris consists mainly of erectile tissue similar to that of the 

 corpora cavernosa of the penis. It is covered with a thin epithelium 

 with underlying papillae, and is richly supplied with nerves having 

 highly specialized terminations. 



' Develop AiEiXT of the Urinary and Reproducti\'e Systems 



The development of the genitourinaty system is complicated by the appear- 

 ance, and disappearance for the most part, of two sets of urinary organs, and 

 the linal formation of the permanent set. The three sets, in the order of their 

 appearance, are the pronephroi, mesonephroi, and metanephroi. The first 

 two sets, which are present only in the embryo in the higher animals, are the 

 representatives of organs that function in the adult in. the lower vertebrates. 

 They are also intimately concerned in the development of the efferent duct 

 system of the male reproductive organs in higher animals. The metanephroi, 

 generally known as the kidneys, are the functional urinary organs in the majority 

 pf reptiles and in all birds and mammals. 



The pronephroi are represented in the human embryo of 3 to 5 mm. by one or 

 two small, condensed masses of mesoderm just lateral to the primitive segments 



