Histomorphology of the Harderian gland in the Angora rabbit

This study was aimed to demonstrate the morphological and histochemical properties of the Harderian gland in the Angora rabbit. Ten healthy adult Angora rabbits obtained from private breeders constituted the material of the study. The Harderian gland, which is composed of the pink and white lobes, consists of cells that produce a secretion of lipid character. The pink lobe contained type I cells with large lipid vacuoles. Cells with small lipid vacuoles (type II) were found in the white lobe. Type III cells containing both large and small lipid vacuoles were not observed. While type I cells reacted strongly to staining with Oil red O, type II cells reacted weakly to this stain. The number of plasma cells was greater in the white lobe when compared to the pink lobe. The apical granules within the epithelial cells lining the intralobular and inter-lobular excretory ducts of the gland were positive for periodic acid-Schiff (PAS), periodic acid-Schiff/alcian blue (PAS/AB), alcian blue (AB) and performic acid/alcian blue (PA/AB). Electron microscopic examination revealed that type I cells contain large electron-light lipid vacuoles and an eccentric heterochromatic nucleus, due to the presence of these vacuoles. The cells, which were connected by tight junctions, possessed apically located microfolds. The nucleus of type II cells was situated basally and had an oval shape. Type II cells had apical microvilli-like cytoplasmic protrusions, longer than those of type I cells. Oval shaped myoepithelial cells were observed between the glandular epithelial cells and their basal lamina. The epithelium lining the excretory ducts of the gland contained two types of granules, which were dark and lightly coloured. Histochemical and ultrastructural examinations revealed no difference in the structure of the Harderian gland between female and male Angora rabbits.