Histological, histochemical and ultrastructural studies on Harderian and lacrimal glands of the Capercaillie (Tetrao urogallus major L.).

This study describes the macroscopic anatomy and the microscopic and ultrastructural features of the Harderian gland and lacrimal gland of the Capercaillies. It was conducted both on adult male and female Capercaillies. Tissue sections were stained with hematoxylin and eosin, azan trichrome, modified Mallory's trichrome, methyl green-pyronin Y, periodic acid-Schiff, alcian blue pH 2.5, aldehyde fuchsin and Hale's dialysed iron. The morphometric study of the Harderian and lacrimal glands indicated that they are both larger in male than in female Capercaillies. The histological analysis showed that the HG has a multilobar tubulo-alveolar structure with numerous lymphocytes and plasma cells. The LG has a multilobar tubulo-acinar structure without lymphocytes and plasma cells. The periodic acid-Schiff staining and alcian blue pH 2.5 staining demonstrated a mild positive reaction in the epithelial cells of the Harderian gland and weak positive reaction in the lacrimal gland. The HDI staining detected the presence of carboxylated acid mucopolysaccharides in the Harderian and lacrimal glands. Transmission electron microscopy revealed the presence of two types of secretory vesicles in the cytoplasm of both studied glands. It also showed that lipid droplets and glycogen granules were more abundant in the Harderian gland than in the lacrimal gland of this species.