Induction of intranuclear inclusions by estrogen in mammotrophs of the mongolian gerbil

Abstract

Inclusions have been induced in the nucleus of mammotrophs in male and female Mongolian gerbils by injection of estradiol. No inclusions could be observed within nuclei of the anterior pituitary gland of control-injected male gerbils, although a small number were normally present within mammotrophs of female gerbils receiving control injections (0.44 ± 0.07 inclusions per field). Estradiol induced 3.30 ± 0.10 inclusions per field in males and 3.90 ± 0.09 for females. Inclusions were of two types: membranous and vesicular. Membranous inclusions were smooth surfaced and consisted of many cisternae containing a slightly electron opaque matrix. Vacuolar inclusions were large, often filling the entire cross sectional area of the nucleus. The protein synthetic apparatus of mammotrophs was stimulated by the estrogen inasmuch as rough endoplasmic reticulum became hypertropic. Inclusions may well reflect the hyperactivity of the mammotrophs after stimulation by estrogen.