Figure 1.

Schematic depicting multiple direct and indirect means by which a toxicant can perturb the epididymis. A toxicant that alters the sperm or fluid leaving the testis (A); the fluid may in turn alter the epididymal epithelial cell function leading to indirect effects on epididymal sperm. Perturbations in the circulation resulting from a testicular insult (B) might exert direct effects on cells comprising the lamina propria surrounding the epididymis or on the epithelial cells. Altered epithelial cell function could again lead to indirect effects on epididymal sperm. A toxicant in the circulation (C) can exert direct effects on the smooth muscle cells in the lamina propria which can lead to alterations in transit, or indirect effects on sperm mediated through secondary effects on epididymal epithelial cell function. Circulating toxicant can also perturb epididymal epithelial cell function directly (D), and this perturbation could then lead to altered sperm function through compromised secretory activity. Circulating toxicant might also cross the blood–epididymal barrier and exert direct effects on the epididymal sperm thereby compromising their function (E). Adapted from Kempinas, W.G. and Klinefelter, G.R. The Epididymis as a Target for Toxicants. In: Charlene A. McQueen, Comprehensive Toxicology, volume 11, p. 152, 2010. Oxford: Academic Press (with permission).