Fig. 2. Immunohistochemical detection of KIN17 (panels A,B,E,F) and PCNA (panel D) proteins during development of mouse testis. Nuclear staining of Sertoli cells (Ser) for KIN17 was observed in testis sections of 1-day-old (panel A), 5-day-old (panel B), 17-day-old (panel E) and 28-day-old (panel F) mice. Nuclei of spermatogonia (Sg), leptotene (S), pachytene (P) and round spermatid (Rs) cells also labelled for KIN17 (panels B,E,F). No staining was detected in gonocytes (unlabelled bold arrows, panel A). Note the nuclear staining of spermatogonia and leptotene spermatocytes for PCNA in 17-day-old testis whereas pachytene and Sertoli cells are unstained (panel D). A control section of a 5-day-old mouse testis is also shown (panel C). Bars, panels A, B and C: 12 µm, panel D: 20 µm, panel E: 18 µm, panel F: 15 µm. In adult mouse testis, staining for KIN17 protein was observed in the nuclei of Sertoli cells (Ser), spermatogonia (Sg) and on chromosomes of cells undergoing mitosis (mi); spermatocyte cells: leptotene (S) zygotene (Z), pachytene (P), early round spermatid (Rs), in the cytoplasm of elongating and late spermatids (Es) and in residual bodies (Rb) (panels G-K). Arrowheads in panel H show nonidentified Es cytoplasmic spherical components. A control testicular section where anti-KIN17 antibody was replaced by normal mouse IgG remained unstained (panel L). Stages of the seminiferous epithelium are indicated with Roman numerals. Bars: panels G, H and J, 12 µm; panel I, 19 µm; panel K, 10 µm and panel L, 11 µm.