GONADOTROPIC SUBSTANCES 



therapy could be attained by administering an extract of 

 pregnant-mare serum. Spermatogenesis reappeared and the 

 accessory organs grew to normal size. The testes of injected 

 animals appeared normal histologically. 



According to Evans and Simpson (1934), atrophy of the 

 thymus of mature or immature rats followed the injection of 

 an extract of placenta or endometrium of pregnant mares 

 This effect did not appear after spaying or castration. Evans 

 Simpson, and McQueen-Williams (1934) studied the effects 

 of the hormone on the pituitary of young and mature rats 

 It produced changes like those of prolan (see pp. 214-15) 

 However, the hypertrophy of the female pituitary was per 

 haps greater than that caused by prolan; in the authors 

 opinion this fact disposes of the theory that the hypertrophy 

 is the result of the increased secretion of a "synergic factor 

 which potentiates the effects of prolan. The "synergic factor 

 does not potentiate the effects of the gonadotropic hormone 

 of pregnant-mare's serum. 



By determining the gonadotropic effect of serum (especial- 

 ly in the second to fourth months) or the effects of the 

 "oestrin" in serum or urine, pregnancy in the mare can be 

 diagnosed with a high degree of accuracy (Zondek, 1930; 

 Ehrhardt and Ruhl, Glud and others, 1933; Greenwood and 

 Blyth, Kiist, Magnuson, Miller, 1934). 



Methods of preparing the hormone from serum or tissues 

 as well as some of the properties of the impure hormone are 

 given by Goss and Cole (1931), Cole, Guilbert, and Goss 

 (1932), Evans, Gustus, and Simpson; Evans, Meyer, and 

 Simpson (1933), and Catchpole and Lyons (1934). 



1^33 



