ABSTRACT
The cell types observed in the epithelium that lines the ductus deferens of the gerbil were principal, basal, narrow, and apical (mitochondria-rich) cells, whose cellular ultrastructure and segmental features were described. The morphological characteristics of the lining epithelium of the ductus in the three main tubular segments: adepididymic (proximal), funicular (middle) and adprostatic (distal) were presented. The cytophysiological role of the epithelial cell types in each segment was discussed on a comparative base. Resorption of seminiferous fluid and adsorptive endocytosis seem to be the main functions of the principal and apical cells. Moreover, secretory functions may occur in both cell types, mainly in principal cells in which ultrastructural characteristics of the Golgi-ER complex had been related to cellular secretion, perhaps of protein. Another ultrastructural feature of the supranuclear cytoplasm of principal cells was the presence of apical cytoplasmic expansions (apical protrusions), observed mainly in the epithelium of the distal ductus deferens segment, with suggestion of apocrine secretory process occurrence.