Histochemical and ultrastructural characteristics of the endometrial connective tissue stroma from mice continuously fed diethylstilbestrol.

Histochemical and transmission electron microscopy were utilized to examine the endometrial connective tissue stroma of mice continuously fed diethylstilbestrol (DES). Virgin female mice were continuously fed diets containing 0, 320, or 640 ppb DES from 4 weeks of age until moribund. All animals reported on in this study were between 622 to 762 days of age when sacrificed. Light microscopy revealed irregular deposits of homogeneous acidophilic material throughout the connective tissue stroma with frequent accumulations seen immediately beneath the surface epithelial layer and surrounding blood vessels. Histochemical results indicated the presence of collagen and fibrin as components of the acidophilic material. Ultrastructural results revealed a homogeneous stroma consisting of short segments of collagen fibrils enmeshed in an amorphous component. Numerous plasma cells were seen in close approximation to macrophages and lymphocytes. Fibroblast cell membranes exhibited micropinocytotic vesicles. Eosinophils were numerous in the stroma and often seen in close approximation to fibroblast projections. Vascular endothelial layers contained numerous micropinocytotic vesicles and marginal flaps. The accumulation of homogeneous material within the connective tissue stroma may represent products from collagen degradation and a subsequent localized immune response as well as plasma components.