The ultrastructure of the epithelium of the ductuli efferentes testis in the common starling (Sturnus vulgaris).

The ductuli efferentes of male common starlings (Sturnus vulgaris) were prepared for light and electron microscopy. The epithelium of breeding birds was pseudostratified, consisting of ciliated cells, which were of the same type throughout the ductules, and of two types of non-ciliated cells: an electron-dense form with complex lateral invaginations, long microvilli and apical invaginations found in proximal ductuli efferentes (Type 1 a) and a less dense, taller, seemingly more secretory cell found distally (Type 1 b). Both types contained crystal-like structures in granular and transitional endoplasmic reticulum, which were occasionally seen in ciliated cells and not elsewhere. These 'intracisternal bodies' were probably proteinaceous in nature. The ciliated cells were typically more electron-lucent than the non-ciliated cells. They adopted the height and interdigitation characteristics of the surrounding epithelium. Occasional annulate lamellae were encountered. Intraepithelial lymphocytes were seen occasionally, notably in non-breeding birds. The epithelial morphology of the non-breeding common starling is briefly mentioned. The tubules were collapsed and apparently inactive, although signs of proliferative activity were seen in birds killed in February. The distinction of the epithelial cells into one ciliated and two non-ciliated types in this study is discussed in the light of previous work, as differences were found to exist. It is suggested that care should be taken in the use of mammalian tubule nomenclature when it is applied to birds.