ESTROGEN AND PROGESTERONE 



571 



Fig. 9.15. Uterus of a castrated monkey which was given 10 yug. estradiol and 2 mg. pro- 

 gesterone daily for 275 days at which time estrogen was stopped and progesterone was con- 

 tinued for 21 days. A shows the thin endometrium and dense stroma whereas B shows failure 

 of formation of a surface epithelium following the loss of the modified functionalis pre- 

 sumably present at the conclusion of treatment with both hormono.^^ (see Fig. 9.13). 



intensified both by cln-onic treatment and 

 high dosage, and seems to be equally ef- 

 fective when it is given alone or in combina- 

 tion with progesterone. Progesterone also 

 promotes growth of the muscularis but 

 seems less effective than estrogen and dif- 

 fers from it by causing pronounced thicken- 

 ing of the walls of the arcuate blood vessels. 

 These vascular changes extend to the coiled 

 arteries of the endometrium, which are also 

 affected by high dosages of estrogen. It 

 seems remarkable that estrogen is capable of 

 preventing the action of progesterone on the 

 myometrial blood vessels and correcting 

 such effects after they are produced and yet 

 at the same time it assists in the destruc- 

 tion of the coiled arteries in the endome- 

 trium. 



V. Experimentally Produced 

 Implantation Reactions 



Progestational endometria of the normal 

 menstrual cycle or those produced in cas- 

 trated monkeys by progesterone, if mechani- 

 cally traumatized, will develop endometrial 

 proliferations which seem identical with 

 those found at normal implantation sites of 

 fertilized ova (Figs. 9.16 and 9.171 (Hisaw, 



1935; Hisaw, Creep and Fevold, 1937; Wis- 

 locki and Streeter, 1938; Rossman, 1940). 

 The proliferated cells originate from the 

 surface and glandular epithelium and grow 

 into the surrounding stroma. The reaction 

 spreads from the point of injury and within 

 a few days may involve the entire inner 

 l)ortion of the endometrium bordering the 

 lumen. The implantation plaques on the 3rd 

 or 4th day present a fairly homogeneous ap- 

 pearance but soon thereafter certain cells 

 attain the proportions of giant cells and 

 many are multinucleated. 



The development of the plaques is most 

 rapid during the first week, by the end of 

 which cell division is found only in the basal 

 half of the proliferation and evidence of re- 

 gression is seen in the superficial portion 

 adjoining the uterine lumen. After 10 days 

 degenerative and phagocytic processes are 

 the dominant features and by 24 days the 

 ut'prus contains few or no ]iroliferation cells. 

 Wislocki and Streeter ( 1938,1 found that im- 

 plantation plaques during pregnancy and 

 those experimentally induced underwent ajj- 

 l^roximately the same development arid 

 subsequent degeneration except for modifi- 

 cations produced by the invading troplio- 



