ABSTRACT
The harderian gland is a large orbital structure which open by a duct onto the surface of the nictitating membrane. It is widely assumed that its primary function is to lubricate the surface of the eye. However, a variety of secondary functions have been ascribed to it, with suggestions that it is a site of immune responses for the conjunctival sac, a source of pheromones and/ or thermoregulatory lipids, a source of photoprotective secretions and part of retinal-pineal axis. By means of histological examination, harderian gland of female guinea pig was investigated to demonstrate the structural appearance of the gland at different age and the results were discussed with reference to functional aspect. A total number of thirty animals of different ages [5 animals each] were used in this study. The ages were [newborn, one week, two weeks, three weeks, two months and six months old]. Specimens from HG of each animal were prepared for light, electron and fluorescent microscopy and immunohistochemical examination. This study revealed that the newborn harderian gland showed signs of maturity features of secretory epithelial cells but continued differentiation with the age. Ultrastucture revealed two types of dark secretory epithelial cells [type I, the principle most common and type II, the vesicular]. The latter possess neuro vesicles with dense cores. Three types of light cells I, II and III present. The chief feature of the cytoplasm of these epithetlial cells was large numbers of lipid vacuoles which dominate the apical half of the cell. Secretory endpieces were surrounded by a network of myoepithelial cells. Heterogenous populations of mast cells with cytopasmic granules in different stage of maturity, size and electron density were detected in intersitium since birth. The glandular epithelial cells fluroscences pale yellow green with fluorescent microscope immunohistochemical result showed some glandular cells with chomogramin positive reaction. The present study will give a systematic description on the structure of the female guinea pig harderian gland at different ages