Cell death in the mosaic epididymis of sex reversed mice, heterozygous for testicular feminization.

Sex reversed mice heterozygous for testicular feminization are genetic females which are converted to males by the autosomal Sxr ("sex reversed") mutation, thus imitating the Y-chromosome. They carry on one of their X-chromosomes the mutation for testicular feminization. Then, X-inactivation leads to the formation of a mosaic of androgen insensitive XTfm and androgen sensitive X+ cells. In the epididymis the Tfm cells are maintained into adulthood as undifferentiated flat cells. There are however, always less Tfm cells than expected from random X-inactivation. Therefore, in the present study the role of cell death in the modification of the original mosaic is investigated before and after castration. It is shown that survival or elimination of Tfm cells depends on the structure of the smooth muscle layers around the epididymal duct. In addition to elimination of whole Tfm sections, a steady loss of single cells, not only in the Tfm but also in the wild-type fraction occurs. In the connective tissue distinct necrotic areas are present. After castration massive necroses appear in both cell types. In Tfm sections disintegration of the wall layers again leads to elimination of Tfm cells and to protrusion of epithelial cells in the interstitium which later on may be organized as abnormal sprouts and ducts. The observations indicate that the testosterone dependent trophic principle is based on short-range intercellular interactions and presumably arises in the connective tissue component of the epididymis.