Postnatal development of mononuclear phagocytes in the mouse epididymis

Abstract

The epithelium lining the epididymis (site of sperm maturation and storage) is surrounded by mononuclear phagocytes (MPs, expressing dendritic cell and macrophage markers) that closely interact with adjacent epithelial cells. We mapped here their distribution during postnatal development in CD11c‐EYFP and CX3CR1‐GFP mice. MPs were present in the epididymis as early as 1 week after birth. The number of epididymal MPs gradually increased and, between week 4 and week 5 (puberty), they underwent major morphological changes. MPs progressively acquired a stellate/dendriform morphology and relocated from the interstitium to the peritubular region. Cellular bodies and lateral extensions were located at the base of the epithelium, while, in the initial segment, slender dendrites extended between epithelial cells towards the lumen. At week 5, MPs had acquired the overall appearance that we described previously in adult mice. In contrast, the peritubular region of the vas deferens (VD) was heavily populated by MPs during the early stages of postnatal development, long before puberty, possibly to prevent ascending pathogens from infecting the developing epididymis and testis. Our data will help better understanding the complex relationships between the immune and reproductive systems during development of the excurrent duct.Supported by NIH‐NICHD grant 1R01HD069623.