Immune response following vasectomy in the rat: a study of the stimulation of the regional lymph node.

Following vasectomy, sperm granulomas are generally believed to be important sites of access of spermatozoal antigens to the immune system. This study tests the validity of that assumption by grafting tissues from a sperm granuloma to an ectopic site (the scrotal skin) and studying the effect on the regional (inguinal) lymph node. Xiphoid cartilage provided the graft material in control animals. The experimental lymph nodes showed significant increases in weight and in the number of sectional profiles of cortical nodules indicating that they were stimulated by the presence of the granuloma tissue. To investigate the mechanism of lymph node stimulation further, a group of rats underwent unilateral vasectomy followed after 7 wk by ipsilateral orchidectomy. Three months after the initial operation the histological features of the regional (left renal) lymph node of the epididymis and granuloma were compared with corresponding nodes from rats 3 months following unilateral vasectomy only and following sham operation. The results indicate that continuous sperm production is required to sustain activity of the regional lymph nodes despite the continued presence of spermatozoa in the sperm granuloma.