Resorption of endometrial collagen in oophorectomized rats.

Uteri of rats that had been either oophorectomized or given a single dose of 17 beta-diethylstilbestrol or progesterone were studied as to the ultrastructural features of collagen resorption by the fibroblasts of the endometrial stroma. Electron microscopy showed several cytoplasmic vesicles within fibroblasts containing collagenous fibrils in various stages of breakdown. These findings suggest that fibroblasts have a collagenolytic action. Hence, this cell type may play a dual role in the metabolism of endometrial collagen - firstly being responsible for its synthesis, and secondly participating in its resorption.