Macrophages of the sperm granuloma 3 months after vasectomy in the Albino Swiss rat

This study documents the appearance and arrangement of the macrophages of t he sperm granuloma 3 months after vasectomy in the Albino Swiss rat. We fou nd, as have others, that the macrophages form a distinct layer in the granu loma wall, external to the central mass of extravasated spermatozoa. Those closest to the spermatozoa showed much phagocytosis. Many had two, three, o r more nuclei. The largest macrophages, giant cells of the foreign body and Langhans types, were generally farther from the sperm mass, but retained e vidence of phagocytic activity in the form of sperm Fragments. Macrophages, either mono- or multinucleate, frequently showed numerous surface microrid ges that interdigitated with those of neighboring cells. The microridges va ried in length, but were of uniform thickness and cytoplasmic content and w ere rarely branched. Monocytes were frequently observed, indicating continu ing significant recruitment of cells of the macrophage series to the granul oma. We also noted mononucleate cells in the connective tissue external to the macrophage layer. Their cytology suggested they were macrophages, but t hey showed much less phagocytic activity than those of the main macrophage layer and had distinctive aggregations of moderately electron-dense droplet s. (C) 2000 Wiley-Liss, Inc.