THE GONADOTROPIC HORMONES 



xAccording to Bachman (1936) interstitial stroma may 

 make up a large part of the ovary of the mature rabbit but 

 largely disappears after hypophysectomy."' Robson's experi- 

 ments in the rabbit (1937) illustrate how rapid regressive 

 changes in the ovaries may render the latter almost unre- 

 sponsive to gonadotropic hormones — i.e., extract of rabbit 

 or horse pituitary or of human pregnancy-urine. A week or 

 more after hypophysectomy, the injection of these hormones 

 had little or no effect on the ovaries, whereas if injections 

 were begun at once, small doses of gonadotropic hormone 

 maintained ovarian function as shown by functional per- 

 sistence of the corpora lutea of pseudopregnancy (8 days) 

 and by ovulation in response to gonadotropic hormone (12 

 days). Other experiments led Robson to conclude that both 

 the pituitary and the ovary are essential for maintaining 

 pregnancy in the rabbit. However, he was able to maintain 

 pregnancy in the hypophysectomized rabbit, for some time 

 at least, by injections of progesterone. The rate of atrophy 

 of the corpora lutea apparently was not affected. It appears 

 that among mammals, the mouse and rat are exceptional in 

 that the corpora lutea in the latter part of pregnancy require 

 no pituitary luteinizing hormone for their maintenance.'' 



Emery (1936) reported that homo-implants of the pituitary 

 in the peritoneal cavity or skeletal muscle of rats apparently 

 lived from several days to a week. Often such grafts became 

 vascularized, retained some gonadotropic potency, and ap- 

 peared nearly normal histologically. Other observations on 

 the secretory capacity of implants or transplants have been 

 made in hypophysectomized mice, rats, and guinea pigs. 



''The observations of Westman and Jacobsohn (1936) on the effects of hy- 

 pophysectomy in the rabbit are largely confirmatory of earlier work. 



■' Houssay (1935) has confirmed the finding that hypophysectomy in the preg- 

 nant dog is followed by abortion or fetal resorption. He stated that even in late 

 pregnancy abortion might appear in 1 days. 



Bellerby (1935) found that the intravenous injection of anterior-lobe extract 

 into pregnant rabbits almost always was followed by abortion or fetal resorption. 

 Ovulation was often produced; hemorrhagic follicles were more frequently produced 

 early or late in pregnancy. 



[65I 



