562 



PHYSIOLOGY OF GONADS 



Fig. 9.4. .4. i'v'< — ' ri:,,ii of the uterus of a cas- 

 trated monkey which had received 1.0 mg. estradiol 

 daily for 35 days. Compare with B which shows the 

 effects of 1/10 this dosage (100 fig. daily) when 

 gi\en for 185 days. 



The limited response of the endometrium 

 to estrogen is in some respects surprising in 

 view of its remarkable growth potentiali- 

 ties and regenerative capacity. These quali- 

 ties were dramatically demonstrated by 

 Hartman (1944) who dissected out as care- 

 fully as possible all of the endometrium 

 from the uterus of a monkey and wiped the 

 uterine cavity with a rough swab and yet 

 the undetected endometrial fragments that 

 remained were capable of restoring the en- 

 tire structure. Also, considering the enor- 

 mous increase in size of the uterus during 

 gestation, it is even more difficult to ac- 

 count for the rather sharp limitation of 

 growtli under the influence of estrogen. 



The increase in tonus of the uterine mus- 

 culature, a known effect of estrogen, has 

 been considered as possibly exercising a re- 

 strictive influence on growth of the endo- 



metrium. An attempt has been made to re- 

 move this containing influence the muscle 

 may have by making an incision through 

 the anterior wall of the uterus (Hisaw, 

 1950) . A castrated monkey was given 10 ixg. 

 estradiol daily for 21 days at which time the 

 operation was performed and the treatment 

 continued with 30 ^g. estradiol daily for 40 

 days. The uterus was laid open by a sagit- 

 tal incision from fundus to cervix and most 

 of the endometrium was removed from the 

 anterior wall. This caused gaping of the in- 

 cised uterus and exposure of the endome- 

 trium on the posterior wall. The incision 

 was not closed and after hemorrhage was 

 completely controlled the uterus was re- 

 turned to the abdomen. 



Examination of the uterus at the conclu- 

 sion of the experiment showed no indications 

 that endometrial growth had been enhanced. 

 The muscularis had reunited and only a few 

 small bits of endometrium were found in the 

 incision (Fig. 9.5). It seemed probable that 

 the purpose of the experiment had been de- 

 feated by rapid repair of the uterus. There- 

 fore, a similar experiment was done in which 

 the musculature of the incised uterus was 

 held open by suturing a wire loop into the 

 incision. Yet the incision closed and no un- 

 usual growth of tlie endometrium was de- 

 tected (Fig. 9.6). 



Observations under these conditions are 

 necessarily limited to those made on the 

 uterus when it is removed at the conclusion 

 of an experiment and comparisons must be 

 made between uteri of different animals. 

 Obviously, it would be more desirable if the 

 response of an individual endometrium 

 could be followed during the course of treat- 

 ment. It is possible to meet most of these 

 requirements under conditions afforded by 

 utero-abdominal fistulae, exteriorized uteri, 

 and endometrial implants in the anterior 

 chamber of the eye. In continuing our dis- 

 cussion we first shall present information 

 obtained by such techni(iues that have a 

 bearing on the response of the endometrium 

 to estrogen. 



The surgical procedure used by Hisaw 

 ( 19501 for preparing utero-abdominal fistu- 

 lae foi' studies of the exj^erimental induction 

 of endometrial growth by estrogen and pro- 

 gesterone was a modification of that used 

 by van Wagenen and Morse (1940) for ob- 



