THE PITUITARY BODY 



animals were studied for more than 6 weeks after hypophy- 

 sectomy. These results are of interest to everyone employing 

 hypophysectomized immature female rats for the assay of 

 gonadotropic hormone. The belief that a rise in ovarian 

 weight takes place about 4 days postoperatively requires 

 confirmation. The authors found that the injection of fol- 

 licle-stimulating hormone into hypophysectomized rats 

 caused an increase in the total number of follicles with a de- 

 crease in the proportion of those which were vesicular. The 

 proportion of vesicular follicles — without any effect on the 

 total number — was increased by the injection of luteinizing 

 hormone. 



Because of the monkey's closer biological relationship to 

 man, the experiments of Smith, Tyndale, and Engle (1936) 

 are of unusual interest. These authors found that marked 

 atresia of follicles, especially of those medium sized or large, 

 followed hypophysectomy in the macaque {Macaca mulatto). 

 Involutionary changes in the endometrium and vagina were 

 as great as or greater than those following spaying. Uterine 

 bleeding for 3-6 days occurred 2-4 days after hypophysec- 

 tomy in the middle of the cycle (stage of follicular growth or 

 proliferation) but was prevented by the daily administration 

 of oestrin. No prolongation of bleeding followed hypophysec- 

 tomy during menstruation. The usual changes in the uterine 

 mucosa were produced by oestrin or progesterone. Uterine 

 bleeding was delayed but usually followed (8 of 10 monkeys) 

 "oestrin-deprivation"; therefore, the authors' results speak 

 strongly against Hartman's view that such bleeding requires 

 a secretion of the pars neuralis. 



In the hypophysectomized and ovariectomized rabbit, the 

 injection of progestin (i rabbit-unit) neither prevents the 

 motility-increasing effect of oestrone on the uterus nor renders 

 the latter oxytocin-insensitive as in spayed rabbits. To pro- 

 duce these effects in the doubly operated animals, the dose 

 of progestin must be increased to 4 rabbit-units (Reynolds, 

 Firor, and Allen, 1936). 



[64] 



