Dynamic expression patterns of Pax6 during spermatogenesis in the mouse.

Spermatogenesis is a series of complex processes to generate mature sperm, and various molecules play crucial roles in regulating these processes. Previous studies imply a possibility that a transcriptional factor Pax6, a key player of brain and sensory organ development, could be involved in spermatogenesis, but neither expression nor function of Pax6 in the adult testis has been examined yet. In the present study, we described for the first time Pax6 expression dynamics in the adult mouse testis. Using cell-type-specific markers, the expression of Pax6 was detected in 67.0% of promyelocytic leukemia zinc finger (Plzf)-positive type A spermatogonia. The expression of Pax6 was also observed in p63-positive spermatocytes and round spermatids. We did not detect any expression of Pax6 in Sox9-positive Sertoli cells or in elongated spermatids and mature sperm. High-resolution analyses revealed that Pax6 formed a single dot-like structure during mid-phase of the pachytene spermatocyte. This dot-like structure co-localized with γH2A.X demarcating XY body, a domain in which X and Y chromosomes are silenced and compartmentalized. These results may suggest a novel role of Pax6 in spermatogenesis.