Ultrastructural characterization of epithelial cells of rabbit harderian gland with particular reference to their mode of secretion

The present study was carried out to shed some light on the ultrastructure of the rabbit Harderian gland in order to help determine its functions with particular reference to the mechanism of its secretion. Twelve adult male and female rabbits were used in this experiment. Small specimens from the Harderian glands were processed for light and transmission electron microscopic study. Obvious structural differences were not observed between male and finale rabbit Harderian glands. The rabbit Harderian gland appeared bibbed; the pink lobe and white lobe. The pink lobe was formed of simple cuboidal epithelial cells with very large lipid vacuoles while the white lobe was formed of simple cuboidal or columnar epithelium with small irregular lipid vacuoles. Lipid vacuoles could be seen in close contact with the plasma membrane at the luminal surface of the acinar cell to be secreted by merocrine mode of secretion. The apical parts of some cells appeared [is being extruded from the cellular apices towards the lumen to be secreted by apocrine mode of secretion. The white lobe contained intraluminal porphyrins accretions, whereas pink lobe lacks these accretion s. The Golgi complexes amid smooth endoplasmic reticulum were well developed in the cells of the white lobe than in those of the pink lobe. The epithelium of the excretory ducts was seen containing apical granules suggesting secretary activity. The glandular stroma possessed unmyelinated axons and capillaries. This study showed that there was no sexual dimorphism in rabbit Harderian: gland. The different mechanisms of secretions were essentially merocrine and an apocrine type, while the holocrine mode of secretion was unconfirmed. The rabbit Harderian gland might also have an endocrine function in addition to its exocrine function