Spermatic granuloma of vas deferens after vasectomy in rhesus monkeys and men: light and electron microscopic study

Spermatic granuloma of the vas deferens is a common complication of vasectomy which has received scant morphologic study. This study investigated the light and electron microscopic structure of such granulomas detected in rhesus monkeys (Macaca mulatta) and man after various modes of vasectomy and postoperative periods. Unilateral experimental vasectomy in monkeys was performed by either silk ligation or clasp occlusion; in 4 of 13 ligated animals and 5 of 5 clasp vasectomized animals granulomas developed at the site of fasectomy. In man, portions of the vas deferens were excised adjacent to the site of vasectomy preparatory to vasovasostomy. Of 5 patients studied, unilateral spermatic granulomas developed in 3. Such granulomas in both monkey and man were characterized by (1) masses of sperm surrounded by epithelioid cells and connective tissue, and (2) multiple epithelial-lined channels which often contained sperm and spermiophages. In both species, fine structural characteristics of the epithelium lining such channels closely resembled those of the principal cells of the normal vas. Spermiophagic cells included macrophages, epithelioid cells, and, in the monkey only, neutrophils. Lymphocytic invasion was a common feature of the human granulomas but was found only occasionally in the monkey granulomas. As a greater number of granulomas are studied in humans and monkeys, it is hoped that the processes underlying granuloma formation and the role of such granulomas in the development of complications after vasectomy will be clarified.