Postnatal differentiation of efferent ductule epithelium in goats: a light microscopic and ultrastructural study

Caprine efferent ductule epithelium contains ciliated and nonciliated cells. The latter cells are divided into three types: type II cells contain PAS-positive granules, type III cells contain PAS-negative vacuoles, and type I cells lack both granules and vacuoles (Goyal and Williams, Anat. Rec. 220:58-67). The objectives of this study are i) to determine when the epithelium differentiates into ciliated and nonciliated cells, ii) to determine when nonciliated cells acquire characteristics typical for type II and type III cells, and iii) to relate developmental changes in the epithelium with those in the testis. Testes and efferent ductules were examined at the light and electron microscopic levels in goats from 1-25 weeks of age. Efferent ductule epithelium contained ciliated and nonciliated cells as early as week 1. While ciliated cells were differentiated at week 1, differentiation of nonciliated cells did not occur until week > or =15. Differential features in ciliated cells included the presence of cilia at the apical border and an aggregation of mitochondria in the apical cytoplasm. Those in nonciliated cells included the presence of i) an endocytotic apparatus at week > or =15, ii) PAS-positive granules at week > or =15, and iii) PAS-negative vacuoles at week > or =25. The seminiferous tubules developed lumens at 12-15 weeks. Hence, while differentiation of ciliated cells occurred much before lumen formation in the seminiferous tubules, that of nonciliated cells coincided with, or occurred soon after, lumen formation, suggesting a role for testicular fluid contents in their differentiation. The goat efferent ductules can be characterized morphologically mature by 25 weeks.