2Q4 HISTOLOGY. 



of the fertilized ovum may be derived from that of the spermatozoon, or from 

 that of the ovum, or arise anew; the evidence is conflicting. Each of the two 

 cells into which the fertilized ovum divides, receives one half- of each of the 

 twenty-four chromosomes, twelve from either parent, and in all subsequent mitoses 

 24 (?) chromosomes appear. This remarkable distribution of chromatin has 

 caused it to be considered the bearer of hereditary qualities. The spermatozoon 

 however, contributes protoplasm to the fertilized ovum and possibly the centro- 

 some also. 



Vessels and nerves. Branches of the ovarian and uterine arteries 

 follow a tortuous course from the hilus to the capillary networks of the tunica 

 interna. They branch freely in the stroma. The veins form a dense 

 plexus at the hilus. Thin walled lymphatic vessels arise in the tunica 

 externa of the corpora lutea and larger follicles, and become more numerous 

 toward the hilus. Their course is independent of the blood vessels, peri- 

 vascular lymphatics being absent. There are no lymphatics in the albu- 

 ginea. Medullated and non-medullated nerves supply chiefly the vessels, 

 but they form terminal nets in the thecae. It is uncertain whether any 

 extend among the follicular cells. Ganglion cells have been recorded 

 near the hilus, but in man the existence of an ovarian ganglion is denied. 

 The principal nerve supply is the plexus of the ovarian artery. 



EPOOPHORON. 



The tubules of the epoophoron presumably vary in structure. They 

 have been described as cords of cells and as tubules lined with simple 

 cuboidal or columnar epithelium, sometimes ciliated. A layer of circular 

 muscles may surround them and internal longitudinal fibers have been 

 found. The epoophoron is of interest as a source of cysts of the broad 

 ligament. Peritonaeal cysts may also occur. 



UTERINE TUBES. 



Each uterine tube is about 5 inches long and extends from its orifice 

 in the abdominal cavity to its outlet in the uterus. It is divided into the 

 fimbriated funnel or infundibulum; the ampulla or distensible outer two 

 thirds, the lumen of which is about a quarter of an inch in diameter; the 

 isthmus or narrow inner third, not sharply separated from the ampulla; 

 and the uterine portion which extends across the musculature of the uterus 

 to the uterine orifice. The tube includes a tunica mucosa, (submucosa), 

 muscularis, and serosa. The mucous membrane is thrown into folds 

 which are low in the isthmus but are tall and branch in the ampulla, the 

 lumen of which they seem to fill (Fig. 337). The branches may anas- 

 tomose; glands are absent. The ampulla has been compared with a 

 seminal vesicle; in it the ovum is probably fertilized normally and the 



