THE GONADOTROPIC HORMONES 



Several observations of general interest should also be men- 

 tioned. Lipschiitz (1936) reported additional studies in 

 guinea pigs from which about three-fourths of the total 

 ovarian tissue had been removed. If the operation was per- 

 formed in new-born animals, it produced little disturbance 

 of the development and function of the genital tract owing, 

 the author concluded, to the great reserve of primordial fol- 

 licles. Sometimes months after the same operation was per- 

 formed in immature animals (13-28 days old), the vagina 

 remained open for abnormal periods and the uterine changes 

 (cystic hyperplasia of the endometrium, etc.) resembled those 

 of metropathic hemorrhage in man. It is not clear to what ex- 

 tent the responsibility for these changes must be attributed 

 to the ovary or to the anterior pituitary or to both. Hamlett 

 (1935) investigated the effects of whole pituitary extract and 

 prolan ("xAntuitrin S") on the genital tract of the armadillo 

 {Dasypus tjovemcijictus). In this animal the blastocyst — i.e., 

 fertilized ovum which has undergone cleavage — lies free in 

 the uterine cavity for four months ("free vesicle period"). 

 Neither hormone hastened implantation; prolan (4 cases) 

 but not pituitary extract (2 cases) caused abortion or re- 

 sorption of the unimplanted blastocyst. Either hormone was 

 found to cause follicle growth, luteinization, and, occasion- 

 ally, ovulation. According to Lipschiitz and Oviedo (1935), 

 the gonadotropic potency (immature rat) of the pituitary of 

 the ratlike South American mammal Myocastor {Myopota- 

 mus) coypu is even lower than that of the female guinea 

 pig despite the animal's size (body-weight as great as 4.5 kg.). 

 Its young, like those of the guinea pig, are well developed 

 when born. Hellbaum's demonstration of differences in the 

 qualitative and quantitative effects of the equine pituitary 

 in the immature rat is of great interest (see Fig. 13). If 

 judgment be based upon ovarian hypertrophy (weight), the 

 concentration of gonadotropic hormone is highest in the pitui- 

 tary of the aged mare and lowest in that of the stallion, fetus, 

 and colt. The potency of the pituitary of the gelding and 



[67] 



