THE PITUITARY BODY 



serum, its effects are not much increased if an anterior 

 pituitary extract is also given (Cole and Hart, 1934). In im- 

 mature male rats the hormone stimulates Leydig's cells, thus 

 indirectly causing hypertrophy of the accessory sexual 

 organs. The testis itself increases in size in part because of 

 the growth of the tubules which contain an increased num- 

 ber of spermatocytes. Cole and others (1932, 1933) have 

 caused ovulation in the anoestrous ewe and oestrus in the 

 young sow by administering the gonadotropic hormone of 

 the pregnant mare. 



In contrast to prolan, but like anterior pituitary extract, 

 the hormone stimulates the gonads of immature birds 

 (Evans and Simpson, Hamburger, Martins, 1934). Particu- 

 larly in the case of the testis of the immature pigeon, how- 

 ever, Evans and Simpson found that the stimulation-dose 

 in terms of rat-units was considerably higher for pregnant- 

 mare gonadotropic hormone than for anterior pituitary ex- 

 tract. Meyer and Gustus (1935) injected a gonadotropic ex- 

 tract of pregnant-mare serum into immature rhesus monkeys. 

 There occurred marked stimulation of follicular growth with- 

 out ovulation or luteinization. With the regression of the 

 ovarian effects specific "antihormone" (not antagonizing pro- 

 lan or gonadotropic extracts of sheep or human pituitary) was 

 found in the monkeys' blood. Engle and Hamburger (1935) 

 found that proliferation of the granulosa of the larger fol- 

 licles was the characteristic effect of the hormone on the 

 monkey's ovary. In the monkey, therefore, it produced an 

 effect like that of the gonadotropic hormone excreted by 

 spayed women. 



The gonadotropic effects of the hormone have also been 

 observed in hypophysectomized rats by Evans, Pencharz, 

 Simpson, and Meyer (1933). In females the ovarian hyper- 

 trophy produced was greater than that following the adminis- 

 tration of anterior pituitary extract and far greater than that 

 following prolan. In males, apparently complete substitution 



[232] 



