Role of Mucopolysaccharides and Lysosomal Hydrolases in Endometrial Regression Following Withdrawal of Estradiol and Chlormadinone Acetate. I. Epithelium and Stroma

Abstract

Electron microscopic subcellular changes of acid hydrolases and mucopolysaccharides (MPS) were studied in endometrium of castrated rabbits treated with estradiol (ED) only, with estradiol and chlormadinone acetate (CA), and during withdrawal periods of both hormones or CA only. Acid phosphatase (AcPase) was identified at electron microscopic level as “marker enzyme” of acid hydrolase activity. Estradiol application initiated formation of numerous lysosomes and depositions of AcPase in Golgi cisternae and vesicles. Treatment with chlormadinone acetate resulted in progestational transformation of estradiol-primed endometrium and a further distinct increase of AcPase activity. After withdrawal of both hormones Ac-Pase becomes, within 48 hr, rapidly engaged in autophagic activities, characterized by formation of autophagic bodies with incorporated cell organelles; autophagic vacuoles in which the organelles have already been digested; and large secondary lysosomes. In the early stages (48-hr withdrawal period) the regressive phenomena are localized within the columnar epithelia of the endometrial lining, later (96-hr withdrawal period) in adjacent stromal areas, and finally at 144-hr withdrawal throughout the entire stromal layer of the endometrium. ED induced accumulation of endometrial MPS. During treatment with CA and periods of hormonal withdrawal a continuous depletion of MPS was observed. Continuation of ED application beyond the period of CA withdrawal prevented formation of autolytic bodies and other lysosomal structures, as well as depletion of endometrial MPS. (Endocrinology85: 50, 1969)