THE GONADOTROPIC HORMONES 



authors to conclude that the secretion of gonadotropic hor- 

 mone is inhibited during lactation. According to De Fremery 

 and Denekamp (1935), doses of pituitary lactogenic hormone, 

 large enough to initiate the secretion of milk, cause abortion 

 or fetal death in utero if administered to pregnant goats, 

 guinea pigs, rabbits, or rats. The lactogenic extract, pro- 

 lactin, of Bates, Riddle, and Lahr (1937) caused as marked a 

 regression of the testes of adult pigeons as hypophysectomy. 

 They believed that the extract did not affect the testes but 

 interfered with the liberation (or formation?) of "follicle-stim- 

 ulating" (gonadotropic) hormone. 



The statements in the foregoing paragraph can soon be 

 tested accurately, inasmuch as the isolation of crystaUine, 

 lactogenic hormone has been announced recently by White, 

 Catchpole, and Long (1937). 



The nervous cont?'ol of the secretion of gonadotropic hormones. 

 — In the discussion of the effect of light and related radiations 

 on the gonads it was emphasized that many of the observa- 

 tions indicate that the secretion of gonadotropic hormones 

 by the pars glandularis may be reflexly stimulated, the affer- 

 ent arc being the optic nerves carrying impulses to the hypo- 

 thalamus, whence secretory fibers pass to the pars glandu- 

 laris. Here it is proposed to review other data which also 

 indicate that impulses from the central or peripheral nervous 

 systems may control the secretion by the anterior pituitary 

 of gonad-stimulating hormones into the blood stream. 



Rosen and Shelesnyak (1937) produced pseudopregnancy 

 in more than one-half of a group of rats as a result of the in- 

 tranasal instillation of a solution of silver nitrate. This effect 

 possibly is related to a reflex effect on the anterior pituitary. 

 Other investigators have studied peripheral sympathetic 

 nerves. Friedgood and Pincus (1935) stated that bilateral 

 faradic stimulation of the cervical sympathetic nerves caused 

 ovulation in 3 of 6 adult rabbits as well as clear-cut matura- 

 tion of ova. In later work Friedgood and Cannon (1936) re- 

 ported that bilateral cervical sympathetic stimulation by a 



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