Effects of estrogen and androgen on the ultrastructure of secretory granules and intercellular junctions in regressed canine prostate

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Abstract
Epithelial cells in the prostate of the castrated or hypophysectomized dog were studied by thin‐section and freeze‐fracture electron microscopy to determine in vivo responses to estradiol‐17β 17‐cyclopentylpropionate (ECP) and testosterone cyclopentylpropionate (TCP). Particular attention was given to changes in specific organelles and intercellular junctions that might reflect hormone action. The few secretory granules that remain in the regressed epithelium (vestigial granules) serve as markers of prior androgen responsiveness. Pharmacologic doses of ECP caused regressed glandular cells to acquire a novel phenotype. Characteristic features of these estrogen‐modified glandular (EMG) cells are newly formed secretory granules and tonofilament bundles that coexist with vestigial granules, thus demonstrating bipotentiality of response. Glandular cell‐tight junctions appear unaltered by the endocrine manipulations. Although EMG cells have squamous cell features, tight junctions remain intact. Desmosomes in the canine prostate are dimorphic and are classified 70F and 100F according to the width of the filaments that converge on the dense plaques. In intact dogs, 100F desmosomes are associated with basal‐reserve cells, whereas only the 70F variety is found between glandular cells. TCP treatment does not alter this distribution. Following ECP administration, both 70F and 100F desmosomes are present between EMG cells. The coexistence of newly formed secretory granules and tonofilaments of 100F desmosomes in the same EMG cell represents estrogen‐induced bidirectional differentiation. Our findings indicate that androgens and estrogens are individually capable of controlling the expression of secretory granules and desmosomes. In intact animals, male and female sex hormones may act in concert to direct epithelial cell differentiation of the prostate.