Ultrastructure of the epididymal epithelium of rhesus monkey (Macaca mulatta)

The regional fine structure of the epithelium lining the epididymis of the rhesus monkey has been investigated. Tall, prismatic principal cells constituted the major part of the epithelium. Their basal plasma lemma showed presence of caveolae and the luminal surface was studded with stereocilis. Presence of numerous desmosomes and tight junctions between adjacent principal cells suggested the existence of blood epididymis barrier. Ultrastructural evidence is presented in support of high lysosomal turnover, absorptive and secretory functions in these cells. Apocrine secretion was evident only in the principal cells of initial segment. Of the two types of basal cell, dark and pale, the latter revealed presence of lipofuscin pigment suggesting their scavenger role in the epithelium.