THE PITUITARY BODY 



(1929) was the first to demonstrate that the gonadotropic po- 

 tency of the pituitary of the adult castrated or spayed rat 

 was increased, as shown by the effects of implants on the 

 ovaries of immature mice and rats. His work was extended 

 in the same year by Evans and Simpson (igig),^^ who con- 

 cluded that the increase in the potency of the pituitary of the 

 donors was greater the longer the period elapsing between 

 gonadectomy and the assay of the pituitary. A similar but 

 less pronounced increase in potency was observed in cryp- 

 torchid male rats. They concluded, moreover, that the in- 

 crease in potency of the female pituitary was greater than 

 that of the male. Gonadectomy was also followed by an in- 

 crease in the weight of the pars glandularis; but this change, 

 unlike the change in potency, was greater in males than in fe- 

 males. ^^ According to Lipschiitz (1933), who used immature 

 female rats for assay, a much greater degree of luteinization 

 is caused by the pituitary of the spayed rat than by that of 

 the adult normal female rat. The experiments of Clark (1935) 

 and Wiesner (1935) in very young rats have already been 

 discussed (see the first section of this division). 



So far, changes in the gonadotropic potency of the anterior 

 lobe as a result of gonadectomy have been demonstrated only 

 in mammals.-'^ The gonadotropic effects of the pituitary of 

 the guinea pig, assayed in mice, are increased after gonadec- 

 tomy (Smith and Engle, 1929); the change is about the same 

 in both male and female guinea pigs (Severinghaus, 1932). 

 Wolfe (1932) performed his assays by producing ovulation in 

 rabbits. He found that the pituitary of the spayed female rat 



33 Also see Emanuel (1931); Higuchi (1931); Emery (1932); and Siegert (1932). 



34 The pituitary of the normal adult female rat — although heavier — contains 

 less gonadotropic hormone(s) than the normal male. 



35 Novelli (1932) reported that the castration of the toad (B. arenarum) did not 

 alter the amount of the pituitary hormone causing ovulation in the female of the 

 same species. Domm (1931) had the impression that the degree of stimulation 

 of the gonads of the immature fowl differed, according to the source of the homo- 

 implants used, as follows: capon > cock > hen. 



