THE GONADOTROPIC HORMONES 



tized rabbit according to the predominant change in the ova- 

 ries. Increased motiHty is associated with follicle growth; the 

 change is in the opposite direction, if ovulation and corpus 

 luteum formation occur. '^ Several other possible interrela- 

 tionships between the uterus and gonadotropic hormones 

 have been studied.''^ Gillard (1937) concluded that hyster- 

 ectomy in the rabbit delays degeneration of the corpora lutea, 

 thus prolonging pseudopregnancy with hyperemia of the 

 mammary gland. In his experiments, pseudopregnancy last- 

 ed about 25 days instead of 18 days in normal animals. 

 Krane's (1937) observations in hysterectomized women, 

 some of whom had been studied as long as 6 years postopera- 

 tively, indicated that in the absence of the uterus there may 

 be cyclic excretion of oestrogen, resembling that in normal 

 women, without any increased excretion of gonadotropic hor- 

 mone. Therefore, hysterectomy is not necessarily associated 

 with a disturbance of the pituitary-gonad interrelationship. 

 In conclusion, data bearing on the number of gonadotropic 

 hormones or their specific effects will be briefly considered. 

 Loeb and his collaborators,^" who performed most of their 

 experiments with immature female guinea pigs, describe the 

 following principal gonadotropic effects: (i) the production 

 of follicular atresia or destruction by "atresin," (2) luteiniz- 

 ing effects on the cells of the theca interna or premature lu- 

 teinization of these cells or maturation of the granulosa of 

 immature follicles, and (3) maturation of the granulosa of 

 large follicles. From a study of the effects of pituitary glands 

 of various animals, of serial implantation, etc., they suggested 

 that these effects might be due to at least three different 

 gonadotropic hormones. More often it is assumed that the 



'' Morgan found that no effects were produced in spayed rabbits. The earlier 

 work of Reynolds indicated that a reduction of motility is to be expected in normal 

 or spayed rabbits after the injection of beef pituitary extract. However, Reynolds 

 referred to tests made 5-7 hours after injection. 



'' See also Hauptstein and Biihler (1936). 



^° Kunkel and Loeb (1935); Loeb, Saxton, and Hayward (1936); Saxton and Loeb 

 (1937). 



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