Effect of Orchidectomy and Chronic Androgen Administration on Thyroid Gland in Adult Male Dogs: a Light and Electron Microscopic Study

This study was to evaluate the effect of orchidectomy and orchidectomy followed by chronic treatment with testosterone propionate on thyroid gland structure in male dogs. Twelve adult male dogs were divided into the sham operated control group (SO), orchidectomized group (Orx) and orchidectomized group treated with testosterone propionate (Orx TP). Thyroid tissue was investigated at both light and electron microscopic levels. In all three groups, both the peripheral and central regions of the thyroid followed similar patterns of histochemical, ultrastructural and stereological changes. Compared to SO dogs, the relative volume densities of the follicles, colloid and epithelium were decreased and that of the interstitium was increased in Orx dogs. The height of follicular cells also decreased significantly in Orx dogs in comparison to SO dogs. Chronic TP treatement of Orx dogs reversed these changes to the pre-orchidectomy state. At ultrastructural level, the thyroid follicular cells of Orx dogs were characterized by decreased number of mitochondria, free ribosomes, lysosomes, colloid droplets and secretory vesicles, apical microvilli and lateral and basal cell interdigitations. Chronic TP treatment of Orx dogs reversed all the ultrastructural changes seen in follicular cells of Orx dogs except those related to the cell membrane.