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 the sperm granuloma 3 months after vasectomy in the Albino Swiss rat. We found, as have others, that the macrophages form a distinct layer in the granuloma wall, external to the central mass of extravasated spermatozoa. Those closest to the spermatozoa showed much phagocytosis. Many had two, three, or more nuclei. The largest macrophages, giant cells of the foreign body and Langhans types, were generally farther from the sperm mass, but retained evidence of phagocytic activity in the form of sperm fragments. Macrophages, either mono‐ or multinucleate, frequently showed numerous surface microridges that interdigitated with those of neighboring cells. The microridges varied in length, but were of uniform thickness and cytoplasmic content and were rarely branched. Monocytes were frequently observed, indicating continuing significant recruitment of cells of the macrophage series to the granuloma. We also noted mononucleate cells in the connective tissue external to the macrophage layer. Their cytology suggested they were macrophages, but they showed much less phagocytic activity than those of the main macrophage layer and had distinctive aggregations of moderately electron‐dense droplets. Clin. Anat. 13:267–276, 2000. © 2000 Wiley‐Liss, Inc.