Observations on multiple sperm granulomas in the rat epididymis following vasectomy.

Seven epididymides of long-term vasectomized rats showing multiple sperm granulomas were studied in serial histological sections. Despite the presence of the multiple granulomas, only two rats showed continuity of the epididymal duct with the central sperm mass of a granuloma. A further three specimens showed breaks in the epididymal epithelium at sites of local distension in the epididymal tail. Granulomas in the epididymal body seem to receive spermatozoa only transiently. The spermatozoa at the center of granulomas in continuity with the epididymal duct showed evenly distributed sperm heads. A number of others showed clumping of spermatozoa, attributed to stagnation of flow and fluid resorption. In many granulomas, folds in the macrophage layer with a connective tissue core rich in lymphocytes and plasma cells projected into the central sperm mass. We conclude that the sperm granuloma is a dynamic structure that shows changes with age and that the sperm granuloma closest to the testis must not be assumed to be the one that is draining the spermatozoa.

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.