The connective tissue ground substance in the mouse uterine cervix: An electron microscopic histochemical study

Sections of uterine cervix from ovariectomized mice treated with relaxin (R) or estradiol benzoate (EB) alone or EB and R in combination were exposed to dialyzed iron solutions prior to epoxy embedding. Control mice were untreated or received the hormone vehicles. Prior to iron staining, some sections were exposed to: (1) 0.05% testicular hyaluronidase for four hours at 37°C; or (2) acidified methanol for four hours at 60°C. Ultrastructurally, the uterine cervical walls from control mice and those treated with R contained densely packed bundles of collagenous fibrils and cells that resembled fibrocytes with few organelles. Except for spurious intracellular iron deposits, there was no iron staining of extracellular components. Fibroblasts of cervices from mice treated with EB or EB and R were larger with highly developed endoplasmic reticulum and Golgi components. Small cytoplasmic vesicles were present close to the cell surface and each contained a thin inner rim of material. The stroma was characterized by widely dispersed bundles of collagenous fibrils in a greatly expanded cervical wall where there was extracellular iron staining that was prominent near cell surfaces and between individual fibrils within an amorphous material. Brief digestion with testicular hyaluronidase resulted in a reduction of extracellular iron staining, although deposits remained adjacent to cell surfaces, between fibrils and within cytoplasmic vesicles. Acidic methylation caused severe tissue damage so that an assessment of iron deposition in thin sections was impossible.