Chap. 18 



REPRODUCTION 



349 



Vaginal Epithelium 



Proliferative Phase Secretory Phase 



Uterine Mucosa 



Fig. 18.13. Diagram showing hormones arising in the anterior lobe of the pitui- 

 tary gland that especially influence the female reproductive cycle. (Courtesy, Pat- 

 ten, Hitman Embryology, ed. 2. New York, The Blakiston Co., 1953.) 



and no embryos be produced. Then the cycle of ovulation and preparation 

 will recur again and again. The human reproductive cycle is substantially the 

 same as that of other mammals although in some respects spectacularly differ- 

 ent from all except monkeys and other primates. The peculiarities of the 

 human cycle can be much more clearly understood against the background of 

 the reproductive cycle as it occurs in the majority of mammals. 



Typical Estrous Cycle. This consists of a cycle of changes in the ovary, 

 accompanied by changes in the entire reproductive tract. As repeatedly stated, 

 the cycle is brought about by hormones of the pars anterior of the pituitary 

 gland acting upon the ovaries, and by those of the ovaries acting upon the 

 pituitary and on the reproductive tubes, especially the uterus, and on certain 



