Postnatal cytodifferentation of the columnar and basic cells in the epithelium of the terminal segment of the ram epididymis

Abstract

The postnatal differentiation of cpithelial cells in the terminal segment of the ram epididymis was studied by electron microscopy. At one week the low columnar cells had little cytoplasm with few and primitive organelles. At two weeks differentiation was already obvious, with an increase in the number of cytoplasmic organelles. Precursors of stereocilia were also seen. At four weeks a mature type of ultrastructure was seen in the distal part of the segment, and at six weeks throughout the whole cauda. Spermatozoe were not numerous until at 18 weeks and then still showed an immature fine structure. Basal cells were seen to form from some columnar cells, which first developed hemidesmomes basally. Later, they lost their luminal contact and their cytoplasm accumulated around a laterally displaced nucleus. Invading cells appeared to be lymphocytes that never showed feathers suggesting a transformation to basal cells. The epithelium of the cauda epididymidis [terminal segment] in rams thus acquires a mature structure at an age when the testis still shows solid cell cords only, which are not likely to produce any fluid for transport into the epididymis.