Localization of Topoisomerase 2 and During the Rat Spematogenesis Cycle

Spermatogenesis involves the processes of germ cell proliferation, meiosis, and maturation. Germ cells at different spermatogenetic developmental stages exist through out the seminiferous tubules. In cross-sections of seminiferous tubules, staging of spermatogenesis is usually performed using PAS-hematoxylin staining, however, most studies also involve immunofluorescence analysis, which can be negatively affected by cell staining. Therefore, finding staging markers compatible with commonly used immunofluorescence techniques could be technically advantageous. In this study rat testis sections were evaluated for immunofluorescence expression profiles of topoisomerase 2 and topoisomerase 2 (Top2 and Top2 ). Stage-specific patterns were seen for both proteins. Topoisomerase 2 was present in the nuclei of the spermatocytes from spermatogenesis stages 7 to 14. Alternatively, topoisomerase 2 was present in the nuclei of elongating and condensing spermatids. It was observed initially as 2-4 small foci in spermiogenesis step 2, then as a single focus near the nuclear membrane of round spermatids from spermiogenesis steps 3 to 8. The Top2 foci were distinct from the chromatoid body and proximal to the Golgi apparatus, which is known to be adjacent to the acrosome. Based on these specific findings we propose that the Top2 locates to the acrosome and that Top2 and Top2 immunofluorescence may be useful staging markers.