Ultrastructural abnormalities of epididymal tissues in XXSxr pseudomale (sex-reversed) mice.

Sex reversed (Sxr), a duplication of the Y chromosomal testis-determining factor in mice, causes testis development in XXSxr animals. No effects of Sxr on nongonadal organs are expected. However, we have previously shown that the epididymis of XXSxr pseudomale (sex-reversed) mice lacks the Initial Segment. In the present study we examined the ultrastructure of the head of the epididymis of adult and 21-day old XXSxr pseudomale mice. Epithelial cells of both adult and juvenile XXSxr animals contain numerous vesicles, some within mitochondria. The basal lamina is thickened and infolded. The periepithelial layer is abnormally thick, with distorted smooth muscle cells and fibrocytes that also contain lysosomelike vesicles, often in mitochondria, and excessively wide intercellular spaces. Normal collagen fibrils are infrequent; they are in part replaced by wisps of nondiscrete material, possibly immature collagen. Sxr is known to affect spermatogenesis and Sertoli cells. The abnormal conjugation of sex-determining genes in XXSxr appears also to subvert mesenchymal-epithelial development in both epididymis and testis. We believe the most likely explanation of our data is that the XXSxr genotype is not testis specific but also influences the epididymis directly.