Regional differences in the morphology of the goat epididymis: A light microscopic and ultrastructural study

Abstract

The goat epididymis, based on morphological differences, was divided into five regions; regions I and II, and the proximal part of region III constituted the head; the distal part of region III and region IV, the body; and region V, the tail. The epithelium of all regions contained principal and basal epithelial cells and intraepithelial lymphocytes and macrophages. In addition, regions II to IV also contained a few apical cells. Clear cells were absent. The epithelium varied in height from the tallest in region I (88 +/- 33 microns) to the shortest in region V (38 +/- 5 microns). Conversely, the luminal diameter, thickness of smooth muscle wall, and luminal sperm concentration were highest in region V. The irregular epithelial height of regions I and IV accounted for a stellate lumen in contrast to the oval lumen of the other regions. Whereas the lumen of region I contained only a few sperm, those of regions II, III, and IV were filled with sperm. Principal cells were the only cell type that showed striking cytological differences between regions. While they contained absorptive features (canaliculi, pinocytotic and coated vesicles, and subapical vacuoles) in all regions, the principal cells of region II were filled with large, heterogeneous vacuoles (up to 5 microns in diameter), suggesting that they may be preferentially involved in transporting and digesting particulate material. Besides absorptive features, principal cells of all regions contained morphological correlates of protein synthesis such as highly developed Golgi complexes in the supranuclear area and numerous cisternae of RER near the Golgi body and in the infranuclear cytoplasm. The cisternae of RER were more developed in region IV, and in some instances, they were distended with flocculent material resembling newly synthesized protein. Unlike the protein synthesizing organelles, principal cells of all regions lacked morphological correlates of steroid hormone synthesis. These results are compared with previously published data on the regional differences in the epididymis of other species, especially with those of the rat and the bull, in an effort to understand the significance of the epididymis in sperm maturation.

Zinc Iodide-Osmium Tetroxide (ZIO) Reactive Golgi Apparatus in the Principal Cells of Dog Epididymal Epithelium

“…Principal cells possess a well-developed Golgi apparatus and numerous rough endoplasmic reticulum cisternae, suggesting that these cells are able to synthesize and secrete proteins or glycoproteins, similarly to what is observed for other mammalian species (Hamilton;Robaire & Hermo;Goyal & Williams, 1991;Arrighi et al).…”

Ultrastructure of the epithelium lining of cauda epididymidis in mongrel dogs

“…Similarly, a few apical cells have been reported in the tail region of the cat epididymis (Arrighi et al 1986, Viotto et al 1996. Basal cells lie on the basal lamina and are characterized by scanty organelles as observed in the goat epididymis (Goyal & Williams 1991). Dadoune (1981) reported that the basal cells function is to renew the principal cells in the epididymis.…”

“…The fine structure of the epididymis of the mammals has been previously described (Hamilton 1975, Goyal & Williams 1991, Orsi et al 1994, Schimming & Vicentini 2001, Lorenzana et al 2007, Beu et al 2009). The lining epithelium of cauda epididymidis in the mongrel dogs contains four cell types: principal, clear, basal and apical cells.…”

“…Golgi apparatus associated with secretory vesicles, scattered mitochondria, and numerous dilated and flattened cisternae of endoplasmic reticulum (Hermo et al 1991, Hermo 1995, are features evident in principal cells of the cauda epididymidis in the dog. The rough endoplasmic reticulum and free ribosomes observed are characteristics of protein synthesis (Hamilton 1975, Flickinger et al 1978, Goyal 1985, Robaire & Hermo 1988, Goyal & Williams 1991, Schimming & Vicentini 2001.…”

“…Thus, the cauda epididymidis is a place for long-term storage of mature spermatozoa. Depression of their metabolism and motility as well as prevention of the acrosome reaction occur in this region (Goyal & Williams 1991).…”