Effects on the efferent ducts in Macaca mulatta.

Immunopathologic findings in efferent ducts of 36 rhesus macaques vasectomized as many as 12 years earlier and of 11 age-matched control animals were compared. Electron-microscopic observation of these ducts revealed changes after vasectomy. The epithelium shortened from a prevasectomy height of 25 mu to 14 mu as the ducts stretched after vasectomy. The number of sperm and macrophages in the lumen increased. The basement membrane was 300-700 A wide in nonvasectomized animals but several times that in animals vasectomized 6 or more years before; the mean width significantly increased with time after vasectomy. Numerous electron-dense immune complexes were found within the thickened lamina in 33% of vasectomized animals and in none of the controls. The mean size of the electron-dense areas varied from 0.01 sq mu in a monkey vasectomized 3 years earlier to 0.18 sq mu in an animal vasectomized 7 years earlier; the mean area significantly increased with time after vasectomy. Frozen sections of testis and epididymis were evaluated through the use of fluorescein-conjugated antibodies. Of the nonvasectomized controls, 18% showed immune deposits. Of the vasectomized animals, 53% revealed C3 deposition in the basement membrane surrounding the efferent ducts. The presence of electron-dense deposits plus the finding of putative immune complexes as revealed by immunofluorescence suggested that vasectomy enhances leakage of sperm antigens, particularly in the region of the efferent duct.