HORMONES AND REPRODUCTION 



59 



The effect on the ovary of the follicle-stimulating- 

 hormone of the anterior pituitary is seen particularly in 

 the later stages of the growth of the primary oocj^e and 

 of its follicle. In the pigeon injections of this hormone 

 cause the rapid growth of the largest oocytes, ^'^^ while 

 in mammals such as rats and monkeys, it causes the 

 rapid enlargement of the Graafian follicles. ^^^ In no case, 



Oogonium 



Germinal 

 epithelium 



Oocyte 



Interstitial 

 tissue 



Graafian 

 Foilisle 



Follicle cells 



Antrum 



Oocyte 



Fig. 7. — A section of the ovary of a 



mouse to- show the developing oocytes 



and follicles. 



however, do these hormones appear to affect the growth 

 of the oogonium or that of the primary oocyte in its 

 earlier period of growth. The approximate stage at which 

 the primary oocyte becomes susceptible to the influence 

 of F.S.H. is, in the egg-laying vertebrates, the time when 

 yolk droplets begin to be deposited in the cytoplasm, 



