THE FEMALE ORGANS OF GENERATION. 245 



found in the muscular coat and mucous membrane. In the 

 latter such reticula are seen to surround the glands. The veins 

 are very large, possess delicate walls, and are valveless. In the 

 cervical portion, a more regular distribution of vessels is met 

 with, and their walls are unusually thick. 



Numerous lymphatic vessels are found beneath the peri- 

 toneal covering of the uterus, and arched passages are seen 

 ending in loops or blind extremities under the mucous mem- 

 brane of the cervix. Lymph clefts and vessels are also met 

 with in the intermuscular connective- tissue. 



The nerves of the uterus are derived from the genital sper- 

 matic ganglia. On the posterior wall of the neck a large 

 ganglionic mass is met with, from which most of the nerves 

 have their origin. Nervous filaments may be followed as far 

 as the mucous membrane, and a few histologists have traced 

 them into the papillae of the cervix, while in the muscular coat 

 they are said to terminate in the nuclei of the muscular ele- 

 ments. 



During the physiological function of menstruation and 

 gestation the uterus experiences certain modifications. In the 

 former there is an increase in the size of the organ, owing mostly 

 to the great increase of blood in the vessels ; the glands of the 

 mucous membrane are also increased in size. The discharge of 

 blood during this period is due either to a rupture of the dis- 

 tended capillaries, or a diapedesis, in which the walls remain 

 uninjured. On microscopical examination of the menstrual 

 fluid it is found to contain, besides the blood-elements, numer- 

 ous uterine epithelial cells. 



The modifications of the uterus during gestation occur es- 

 pecially in the muscular elements, which are greatly hyper- 

 trophied, and there is also a new formation of them. The 

 blood-vessels, lymphatics, and nerves also experience an in- 

 crease in size, the latter by a thickening of their perineurium. 

 The mucous membrane of the body of the uterus during gesta- 

 tion is separated from the uterus, previously becoming thicker, 

 softer, and more vascular, and constitutes the decidua. The 

 cervical portion of the mucous membrane does not participate 

 in this metamorphosis ; it retains its epithelium, and secretes a 

 mucous plug, which fills the canal of the cervix during preg- 

 nancy. Subsequent to delivery a new mucous membrane and 

 glands are developed on the cavity of the uterus, and the hy- 



