The structure and fuction of the Epididymis. 1. The histology of the Rat Epididymis.

Abstract

Epididymides from six white rats have been examined by standard histological techniques. The epididymis, consisting of rete, efferent ducts, and epididymal duct possesses an epithelium containing six cell types-principal, basal, ciliated, apical, halo, and clear cells-each of which is described. Cytoplasmic differences in the principal cells permit two zones to be recognized in the efferent ducts. The principal cells along the length of the epididymal duct vary in a number of features such as: height, depth and distribution of staining, the incidence, size, and intracellular distribution of vacuoles, the shape of the nuclei, and the distribution of chromatin within them. Such differences permit definition of six major zones, some of which may be further subdivided. Variations in the histological characteristics of the various zones in different individuals have been described. These zones have been related to the usual anatomical divisions of head, isthmus, and tail. The lumen of the epididymis contains spermatids and their breakdown products in addition to spermatozoa. The latter vary in density (number per unit volume), and in their arrangement with respect to one another, in the various zones of the efferent epididymal ducts. The implications of these histological findings in the physiology of the epididymis are discussed.