Uterine and Extrauterine Localizations of Experimental Fibroids Induced in Guinea Pig by Prolonged Administration of Estrogens. ∗

Abstract

The occurrence of uterine fibroids was reported in a number of guinea pigs treated for several months with estrogens. 1 Extrauterine abdominal fibroids also were induced in guinea pigs injected sub-cutaneously with estrogens in the course of 4 months. 2 Fibroids appear even if quantities as small as 5 γ of the monobenzoic ester of estradiol per injection or a total of 400 γ are given in the course of 3 months.† All estrogens, free or esterified, natural or synthetic, proved to be tumorigenic. 3 Tablets of estradiol introduced beneath the skin may induce fibroids as early as in 3 weeks. 4 There is an enormous variability as to the localization of uterine and extrauterine fibroids, although when a sufficient number of animals is observed, some typical localizations can be established. A survey of these localizations of experimental fibroids is given in the present paper (Figs. 1-16) based on the results of the autopsy of several hundred females to which the following 10 estrogens were administered : estrone, estriol, estradiol, 4 esters of the latter (monoben-zoate, monocaprylate, dipropionate, 17-benzoate-3-n-butyrate), stil-bestrol, dipropionate of stilbestrol, hexestrol.

Uterine tumors are mostly subserous (Figs. 3, 4, 14-C) and can become pedunculated (Fig. 2). Very often they are to be found in the mesometrium (Figs. 6, 8); intramural fibroids and those of the submucosa are rare (Fig. 9). The whole surface of the uterine stem and part of the uterine horns may be covered by an extensive fibroid (Fig. 1). The angle between the horns is often the site of a tumor. There may be also a chain of small tumors on the ventral surface of the uterus (Fig. 5).