Abstract
The ductus epididymidis of adult dogs (1.5-2 years) could be histologically divided into four segments.
1) Segment I occupied the greater part of the caput epididymidis with the ductuli efferentes, corresponding to "initial segment" (Glover & Nicander, 1971). This segment showed a higher epithelium with longer stereocilia. Principal cells had well-developed Golgi apparatus and abundant rough endoplasmic reticulum.
2) Segment II was situated in the dorsal part between the caput and corpus epididymidis, corresponding to the proximal one-third of "middle segment" (Glover & Nicander, 1971) and "subsegment I" (Sinowatz et al., 1979a). Spermatozoa were rather few. Principal cells had numerous vacuoles containing various electron-dense flocculent material.
3) Segment III occupied the greater part of the corpus, corresponding to the distal two-thirds of "middle segment" (Glover & Nicander, 1971) and "subsegments II to IV" (Sinowatz et al., 1979a). This segment showed a narrow lumen containing numerous spermatozoa. Principal cells had many lysosomes, some fragments of spermatozoa and huge vacuoles.
4) Segment IV was located in the cauda, corresponding to "terminal segment" (Glover & Nicander, 1971). This segment showed a wider lumen and a lower epithelium with shorter stereocilia. Spermatozoa were densely crowded. Principal cells had many lysosomes.
