Liposome-mediated macrophage depletion: an experimental approach to study the role of testicular macrophages in the rat.

Liposome-entrapped dichloromethylene diphosphonate was injected locally into the right testes of adult rats. This treatment, which has been found to deplete resident macrophages in some other organs, reduced the number of testicular macrophages by at least 90%. Testicular weight and seminiferous tubule morphology were unaffected by liposome treatment. Leydig cell testosterone secretion gradually declined in the macrophage-depleted testes, and there was a compensatory increase in Leydig cell size and testosterone secretion in the contralateral saline-injected testes. These observations suggest that macrophages influence Leydig cell function locally. It is concluded that liposome-mediated depletion of testicular macrophages may serve as an experimental model with which to study the physiological role of these cells.