Ultrastructural features of epididymal spermatophagy in subfertile chromosomally derived mice

A cytochemical analysis of aneuploid gametes in chromosomally derived subfertile mice has demonstrated a prezygotic selection against the aneuploid gametes during the epididymal transit. The present investigation deals with an electron microscopic analysis of the epididymis in subfertile hybrid mice heterozygous for eight Robertsonian metacentrics. The epididymal epithelium of these mice appears to be formed by four cell types with different morphological features. In the tail of the epididymis all these cell types are present. Moreover, several giant vacuolizations of principal cells containing mature and immature spermatozoa are often visible in this region. This observation, confirming previous data on the fate of aneuploid spermatozoa on hypofertile Robertsonian heterozygotes, suggests a phagocytic activity of the epididymal epithelium of these mice. The epididymal epithelium "filter function" in recognizing and eventually disposing of immature or anomalous germ cells is discussed.