Yq deletion and failure of spermatogenesis.

The spermatogenesis of a sterile male carrying a Y long arm deletion was analyzed by meiotic techniques and by light and electron microscopy on testicular biopsies. R-, Q- and C- banding techniques have shown that the Y long arm deletion included the entire heterochromatin and a part of the euchromatic region, with breakpoint between q11.21 and q11.23. The seminiferous tubules showed a sharp decrease in spermatogonia, degenerative phenomena in their nuclei and a spermatogenic block. Abnormal meiotic aspects were observed: pairing failure with atypical diakinesis configurations. These findings confirm the presence of spermatogenesis controlling factors on the distal euchromatic region of the Y long arm.