Gross, histological and ultrastructural features of the bulbourethral gland in the greater cane rat (Thryonomys swinderianus).

The present study examines the structure and ultrastructure of the bulbourethral glands in 10 sexually matured male greater cane rats raised in captivity. Following anaesthesia, the rats were perfusion-fixed transcardially and the bulbourethral glands dissected out. Upon morphologic and morphometric analysis, the Cowper's glands were observed to have an average volume of 0.24±0.08 ml, a diameter of 6.3±0.6 mm and weighs 0.199±0.06 g. The paired, gourd-shaped tubuloalveolar glands were surrounded by dense connective tissues and separated into lobules by capsular septae. Each lobule consists of endpiece/secretory units and excretory ducts lined by simple glandular epithelium and pseudo-stratified epithelium, respectively. The round end pieces consisted of 8-10 pyramidal to columnar epithelial cells with flattened, basally located nuclei and granule-filled cytoplasm that bounded a narrow glandular lumen. The striking ultrastructural features of these secretory cells were the presence of some granules with uniform electron density and those with regions of lesser density as well as the absence of secretory vacuoles. Another unique characteristic of these secretory granules is the presence of electron dense strands radiating from their surfaces. The apical surfaces of the cells were also studded with abundant microvilli. From the findings, the structure of bulbourethral glands in the greater cane rat shows more resemblances to that of humans than to its rodent phylogeny. These findings serve as additional knowledge in the structural interpretation of the bulbourethral gland and its secretory products.