Sequential histology of the adult chimpanzee epididymis

The chimpanzee epididymis consists of three gross anatomical regions: caput (Cp), corpus (Cr), and cauda (Cd). During epididymal transit, chimpanzee sperm undergo maturational changes (affecting motility, capacitation, and the acrosome reaction), which enable fertilization. Elucidation of the sequential histology of the chimpanzee epididymis is preliminary to determining the role of each region of epididymal duct in the process of sperm maturation. We report the histology, in the adult male chimpanzee, of sequential segments of epididymis from the proximal efferent ductules through the Cp, Cr, and Cd regions of the epididymis proper to the proximal ductus deferens. These data illustrate the gross architecture of the tissue and reveal the histology characteristic of the diverse epithelia composing the epididymal ducts at each level. The tubules composing the epididymis of the adult male chimpanzee present at least 16 histologically-distinct epithelia and their transitional forms. Such diversity of epithelia suggests a corresponding diversity of function. Although there are some clear differences, the histological appearance of the ducts, and of the component epithelia of the chimpanzee epididymis, is remarkably similar to that reported for the human.