Identification and characterization of mononuclear phagocytes isolated from rat testicular interstitial tissues

Rat testicular interstitial tissues contain numerous mononuclear phagocyte-like cells. Dispersed testicular tissues are allowed to settle onto a glass substrate and the strongly adherent cells are identified as the same cells that have been described in vivo, based on the retention of an in vivo marker (plutonium). These putative testicular intersitial tissue macrophages (TIMs) have adhesion and cell surface features characteristic of mononuclear phagocytes, as determined by scanning electron microscopy. Immediately after isolation from testicular tissues, TIMs show a strong staining reaction for nonspecific esterase. These cells have Fc and complement receptors and some express Ia cell-surface antigens. About two thirds of the TIMs phagocytose sheep red blood cells and most of the cells are capable of nonspecific phagocytosis of polystyrene beads. This study demonstrates that the phagocytic cells found in testicular interstitial tissues have morphological, histochemical, phagocytic, and immunological properties characteristic of functionally active mononuclear phagocytes. These results suggest that these resident mononuclear phagocytes may play a role in immune-related functions in the testis.