Spontaneous accumulation of eosinophils and macrophages throughout the stroma of the epididymis and vas deferens in alymphoplasia (aly) mutant mice: I. A histological study

PROBLEM: The alymphoplasia (aly) mutation of mice causes the systemic absence of lymph nodes and Peyer's patches. Histopathological analysis has revealed that lymphocytes accumulate in some organs such as the salivary glands, lungs, kidneys, liver, and pancreas of homozygotes (aly/aly) but not heterozygotes (aly/ + ). However, the presence of lymphocytic accumulation in male reproductive tissues of aly/aly mice has not been reported. METHOD OF STUDY: The male reproductive organs of homozygous aly/aly, heterozygous aly/ +, and other immunodeficient mice bred in a specific pathogen-free state were histologically investigated. RESULTS: Testes, ductuli efferentes, prostates, coagulating glands, and seminal vesicles of homozygous aly/aly mice were free from any pathological accumulation of leukocytes. However, their epididymides and vasa deferentia exhibited massive infiltration by leukocytes, which were composed of eosinophils and macrophages. In all homozygotes examined, both eosinophils and macrophages were extensively observed throughout the stroma of the epididymis and vas deferens, but never within the epithelium or lumen of the ducts, with no parenchymal tissue damage. The accumulation of eosinophils was never found in nonreproductive organs. In aly/ + heterozygous mice and other immunodeficient mice, no pathological accumulation of leukocytes were noted. CONCLUSIONS: The accumulation of eosinophils and macrophages is specific to the epididymides and vasa deferentia of immunodeficient aly/aly homozygotes, although the pathogenesis remains unknown.