Development of harderian gland in female guinea pig: histological and ultrastructural study

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

comparative study of the harderian gland in the female rat and female rabbit [A histological, histochemical, scanning electron microscopic and morphometric study]

The Harderian gland [HG] is a large retrobulbar, tubuloalveolar organ. It is present in many animals possessing a nictitating membrane [third eye lid]. Compare the microscopic features of the HG in the female rat [as n example of rodents] with those of the female rabbit [as an example of mammals]. Using histological, histochemical and morphometric techniques on the HG in adult female rat [3 months old] and rabbit [4.5 months old]. A total number of 6 adult animals were used in each species. By gross inspection the Harderian gland is bibbed. In the rat, the two lobes are similar in colour and texture while in the rabbit, the small lobe is white and the large lobe is red [pink]. The gland is covered by a thin C.T. capsule with species variations both in structure and auto fluorescence. In the rat the two lobes show a fundamentally similar histological structure and the secretory epithelium is formed of two types of cells, type A and type B. While in the rabbit the two lobes have different histological structure and each lobe is formed of a single type of cells that differs in both lobes. The contents of the lumina of the tubuloalveoli vary in the two species indicating different modes of secretion. Statistical difference in the arbitrary area of the tububoalveoli between the large and small lobes of the gland is insignificant in the rat but it is significant in the rabbit. In both species a single extra glandular excretory duct is detected at the hilum of the gland. In the rat the wall of the duct possess diverticula and the lining epithelium comprises some serous/or mucous acini. While in the rabbit, the structure of the duct is simple and it is lined by a low columnar epithelium with some goblet cells. Further research will be needed to correlate the different histological structure between the female rat and rabbit HG with the biology of these animals and to their functional significance

New and peculiar cytoplasmic membranous bodies in the acinar cells of the harderian gland of the armadillo Chaetophractus villosus

A new and peculiar morphological feature in acinar cells of the Harderian gland of the South American armadillo Chaetophractus villosus (Mammalia, Dasipodidae) is reported. The gland of adult males and females was studied at macroscopic, microscopic and electron microscopic levels. The gland is the largest structure in the bony orbit. It is located in its medial (nasal) and basal side. It shows a tubuloalveolar structure characterized by large alveoli with a single layer of columnar or cuboidal cells. Myoepithelial cells are located between the secretory ones and the basement membrane. The peculiar morphological feature consists of large intracellular membranous bodies located in the supranuclear cytoplasmic region. They are seen in every acinar cell of males and females. Their size is prominent being almost as large as the nucleus. Only one body is observed in each cell. The structure of the bodies displays an outstanding geometrical pattern which differs completely from other membranous structures described in other species.