Degenerated tubules in the guinea pig testis after long-term vasectomy or sham operation

The testes of eight unilaterally vasectomized and six sham-operated Dunkin Hartley guinea pigs were examined 3 years after operation by wax and resin histology and transmission electron microscopy. Degenerated tubules are rep orted that were common on the side of vasectomy but also found in the contr alateral testes and in the controls. A central accumulation of macrophages, rich in phagocytosed debris including spermatozoal fragments, was surround ed by attenuated Sertoli cells, a markedly thickened basement membrane and myoid cells. At some sites macrophages impinged directly on the basement me mbrane. They probably represented highly degenerated seminiferous tubules. The study suggests that the response to injury of seminiferous tubules may show species variations. Macrophages did not feature in the degenerated sem iniferous tubules we reported following vasectomy in the rat. However, the rat showed striking changes in the morphology of the basal laminae and myoi d cells which did not occur in the guinea pig. Pathological changes have be en reported in the human testis following vasectomy but their etiology is u nclear. Studies in the guinea pig are enhancing understanding of the mechan isms and features of testicular damage. Clin. Anat. 13:6-10, 2000. (C) 2000 Wiley-Liss, Inc.