Peritubular macrophages phagocyte remains of undifferentiated spermatogonia in mouse testis

The cells involved in spermatogenesis are germ-cells, called spermatogonia, classified as: type A-undifferentiated, type A-intermediate and type B. During the spermatogenesis, more than 75% of the germ-cells undergo apoptosis and most of them are phagocyted by Sertoli cells. Peritubular macrophages in adult mouse testis are macrophages that both stimulate the proliferation and differentiation of undifferentiated spermatogonia in the wall of the seminiferous tubule. They have long processes and ramified appearance that squished between the lateral sides of neighbor myoid cells. We show, that a population of peritubular macrophages, grouped in pairs and activated, phagocyted undifferentiated spermatogonia in apoptosis. In adult mouse testis, 3.3x 10 5 undifferentiated spermatogonia are in the germinal epithelium and 8,250 of them are in apoptosis. We counted in the testis 2,634.2 ±160 peritubular macrophages with phagocytic activity. If each one phagocyted one undifferentiated spermatogonia in apoptosis, it may indicated that peritubular macrophages phagocyted 31.9 % of the total undifferentiated spermatogonia in apoptosis. According to our knowledges, this is the first time that it is shown that undifferentiated spermatogonia in apoptosis are cleaned by peritubular macrophages. Summary Sentence We report that peritubular macrophages of adult mouse testis, phagocytic remains of apoptotic undifferentiated spermatogonia. These results show that peritubular macrophages, like Sertoli cells, participate in the remotion of germinal cells in the testis.