THE PITUITARY BODY 



extract, whereas regression of the interstitial cells was pre- 

 vented only by luteinizing hormone. 



SPECIAL CONSIDERATIONS 



The secretion of gonadotropic hormones in relation to sex and 

 the internal secretions of the gonads, i . T)iferences related to 

 sex and age. — McQueen-Williams (1935) studied the gonado- 

 tropic potency of the pituitary of rats of different ages and 

 sexes. Her data supplement those of Clark previously re- 

 ferred to. McQueen-Williams performed her assays by means 

 of intramuscular implants in immature female rats, whereas 

 Clark used immature mice for assay. Both authors found 

 that the female pituitary is much the more potent in rats 

 about 3 weeks old, whereas in adult rats the male pituitary 

 is richer in gonadotropic hormone. One important change en- 

 countered by McQueen-Williams was a remarkable increase 

 in the potency of the pituitary of male rats 27-30 days old, 

 the pituitary then being more potent than at any other age 

 studied. The gonadotropic potency of the pituitary of male 

 rats only a week older was again low and did not rise until the 

 animals were more than four months old.^^ Bates, Riddle, 

 and Lahr (1935) compared the concentrations of gonado- 

 tropic hormone in the pituitary of the ox (embryo, calf, adult 

 steer [castrated male], adult bull, normal cow, and cow in 

 early and late pregnancy.) Gonadotropic hormone was de- 

 termined by its effect on the testis of the immature dove. The 

 authors concluded that the only significant differences were 

 (i) the low potency of the steer's pituitary (concentration 

 about 23 per cent less than the average of others) and (2) the 

 high potency of the pituitary of the cow in early pregnancy 

 (concentration about 36 per cent more than the average of 

 others). The low potency of the steer's pituitary is surpris- 

 ing; also, it might be expected that the pituitary of pregnancy 

 would be poor rather than rich in gonadotropic hormone. In 



'■'^ The pituitaries of rats between the ages of forty-four days and tour months 

 were not investigated. 



[76] 



