Effects of High Estrogen doses on the Endometrium

Abstract

The application of high dose estrogens (up to a total of 25 mg of ethinylestradiol in five days) resulted in marked endometrial edema with stromal lacerations and severe hyperemia, together with a retardation of the secretory transformation by 3 to 4 days. There were disturbances both of glandular mucus production and of reticular fiber structure in the second half of the cycle. The secretory transformation is arrested in the third to fourth day stage of a normal spontaneous cycle. The endometrium desynchronized by high dose ethinylestradiol therefore is not more a nidation-endometrium. Similar endometrial pattern (like those after high dose ethinylestradiol) were seen in rhesus monkeys given postcoital doses of estrogens and infertile woman with atypical secretory endometria. These morphological changes seem to be the basis of nidation-inhibition by the “morning after pill.”