ZNT7 and Zn2+ are present in different cell populations in the mouse testis.

The aim of the present study was to investigate the relation of the spatial distribution between ZNT7 and chelatable zinc ions in the mouse testis. Immunohistochemical results demonstrated a wide distribution of ZNT7 in both seminiferous tubules and interstitial tissues of the testis. The spermatocytes and spermatids in the seminiferous tubules showed strong ZNT7 immunoreactivity whereas zinc autometallographic (AMG) staining was absent. Spermatozoa showed a high level of free zinc, but were void of ZNT7 immunoreactivity. No ZNT7 immunoreactivity and AMG grains were found in spermatogonia. Both ZNT7 and chelatable zinc were detected in Sertoli and Leydig cells. Furthermore, double immunofluorescence study demonstrated that the ZNT7 staining overlapped with that of TGN38 (a trans-Golgi marker), suggesting that ZNT7 was localized in the Golgi apparatus in the ZNT7-positive cells. In conclusion, ZNT7 and chelatable zinc were distributed in different cell populations except for Sertoli and Leydig cells in the mouse testis. ZNT7 may be involved in zinc transportation into the Golgi apparatus for protein packaging in the mouse testis.