GONADOTROPIC SUBSTANCES 



gated). Catchpole and Lyons favored the belief that the 

 hormone is secreted by the chorionic epithehum.-*" 



The effects of this gonadotropic hormone resemble those 

 of the anterior pituitary rather than those of prolan. ^^ Its 

 administration to immature female rats produces, initially 

 at least, a hypertrophy of the ovaries roughly proportional 

 to the dose (see Fig. 42). It causes follicular growth and 



0.01 0.1 0.2 0.5 0.4 0.5 0.6 0.7 0.8 0.9 1.0 20 



cc. OF Pregnant Mare's Serum Injected 



Fig. 42. — The relationship between the dose of pregnant mare's serum and 

 ovarian weight in immature rats. Each point represents the average weight of the 

 paired ovaries of four rats. Adapted from Figure 2 of Cole and Hart (1930). 



maturation far exceeding that observed after the injection 

 of prolan. Administered in small doses, it may cause ovula- 

 tion; large doses, however, bring about luteinization without 

 ovulation. In comparison with (prolan or) normal horse 



^° Evans, Meyer, and Simpson (1933) stated that the anterior pituitary of the 

 pregnant mare contains much gonadotropic hormone even late in pregnancy, when 

 none can be detected in the blood. Catchpole and Lyons, however, later showed that 

 a marked reduction in the gonadotropic potency of the anterior lobe occurs in the 

 latter part of pregnancy. 



■t' Cole and Hart (1930); Cole, Guilbert, and Goss (1932); Evans and others 

 (1933); Evans and Simpson, Hamburger (1934)- 



[231 1 



