Studies of the deferent ducts from the testis of the African elephant, Loxodonta africana. I. Structural differentiation
Jones, R.C.; Brosnan, M.F.
Journal of Anatomy 132(Pt 3): 371-386
1981
ISSN/ISBN: 0021-8782 PMID: 7298489 Document Number: 182207
Elephant testes are located medial to the kidneys and their excurrent ducts are also located deep within the abdominal cavity. Each ductulus efferens (there are about 20) is highly convoluted and anastomoses along the proximal 1/3 of its length. The lining epithelium is a low pseudostratified columnar type composed of mainly ciliated and stereociliated cells and some basal and halo cells. The ductus epididymis is lined by a pseudostratified, stereociliated, columnar epithelium which is considerably folded towards each end of the duct. The epithelium is composed mainly of stereociliated principal cells and some basal, apical and halo cells. The epididymis is structurally differentiated along its length. It is anatomically differentiated into a thick, proximal head, which courses over the superior pole of the testis, a thinner, distal tail (where the duct is swollen with spermatozoa), located towards the posterior end of the abdominal cavity and an even thinner isthmus which courses under the dorsal wall of the abdominal cavity and joins the 2 thicker regions. The duct has 3 histologically distinct segments. The initial segment has a narrow lumen containing few spermatozoa and it is lined by high epithelium with long stereocilia. The terminal segment of the duct has a wide lumen and is packed with spermatozoa. It is lined by a low epithelium and is surrounded by a thick layer of smooth muscle. The middle segment is a transitional region between the other 2 segments. It is characterized by very tall epithelium (with long stereocilia) containing numerous lipid droplets and a narrow lumen containing a dense spermatozoa concentration; it appears to be the site of sperm maturation. The ductus deferens is loosely coiled and has a thick muscular wall. The lining epithelium is made up of principal (cuboidal) and basal cells and is extensively folded.