Pattern of ribonucleic acid synthesis in vitro in primary spermatocytes from mouse testis carrying an X-autosome translocation.

In an attempt to elucidate the mechanism of sterility of X-autosome translocations in the mouse, we studied the distribution of [3H]-uridine incorporation in sterile males carrying the balanced X-16 reciprocal translocation. The results failed to show an overall reactivation of the X as has been postulated by Lifschytz and Lindsley (1972) but there was some spreading of X inactivation along the translocated and normal chromosome 16 in those regions that were close to the X breakpoint. We feel that this process could be responsible for metabolic disturbances leading to degeneration of primary spermatocytes and, therefore, to sterility.