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

Histological and physiologycal effects of dopamine-D3 receptor agonist [7-OH-DPAT] on the kidney and adrenal gland of adult male rabbits

This experiment was undertaken to evaluate the effect of D3 [dopamine receptor] activation by intravenous infusion [iv] of 7-OH-DPA T [as specific D3 receptor agonist] on the structural and functional activity of the kidney and adrenal gland and to evaluate the possible mechanism[s] of its action. This study was carried out on 36 adult male Balady rabbits weighing 1.2-1.5 kg body weight. Animals were divided into four groups, one as a control and three groups were used to assess the effect of iv infusion of 7-OH-DPAT at a rate of 0.01, 0.05, 0.1 ug/kg/min for 120 mm. Rabbits were randomly assigned into renal and adrenal assessments. This experiment revealed that activation of D3 receptors, especially with the high dose, was associated with marked dilatation of glomerular blood capillaries and blood vessels among tubules, Structural changes in the juxta glomerular apparatus with signs of degeneration in the macula densa cells were observed. Reduction and distortion of the brush border of the proximal convoluted tubules [PCT,] was noticed. Ultrastructural changes were characterized by dispersion of the ribosomes, numerous cytoplasmic vacuoles, chromatin condensation, and presence of cytoplasmic inclusion bodies. Alteration in the size and morphology of mitochondria, associated with widening of the basal enfoldings were observed, Physiological assessment revealed dose dependent increase glomerular filtration rate, a significant increase in mean levels of urine flow rate, Na excretion rate and K excretion rate. Also, significant decrease in the angiotensin-converting enzyme activity was observed in this work. This study also, revealed involvement of the cells of the adrenal cortex and medulla with variable degrees of degenerative changes, including congestion of the blood capillaries and disarrangement of the zona glomerulosa cells which were occupied with darkly stained cytoplasmic granules. Decreased activity of the zona glomerulosa, was manifested by decrease in aldosteroene secretion, decrease in serum sodium and increase Na excretion rate

Injurious effect of X-ray irradiation on albino rat enterocytes and potential radio protective effect of melatonin [histological and morphometric study]

Radiation enteritis is a significant clinical problem in patients receiving ionizing radiation directed at the abdomen or pelvis. Although radiation therapy is aimed to be directed against the malignant tissue, adjacent healthy tissues are also affected and the small intestine is the most sensitive organ to radiation. Melatonin has been documented as a direct free radical scavenger and an indirect antioxidant, as well as an important immunomodulatory agent. The aim of the research is to study the histological and ultrastructural changes of X-ray irradiation on rat jejunal mucosa and possible radioprotective role of melatonin. Thirty six adult male albino rats were included in the study and were divided into three groups, the first group was included twelve rats and was served as controls, the second group was included 12 rats and was exposed to a whole body X-ray irradiation dose of 8 Grays [Gy]. The third group was included twelve rats and was subjected to intraperitoneal injection of melatonin [10 mg/kg body weight melatonin one hour before irradiation]. The animals were anaesthized at 48 hours after X-ray irradiation and perfused with fixative solution and laparotomy was performed. Immediately after laparotomy, the small intestine [jejunum] was removed. Some specimens of jejunum were fixed in 10% neutral-buffered formalin, embedded in paraffin, sectioned and stained with haematoxylin and eosin. Other specimens were fixed in 5% buffered glutardehyde and electron microscopic technique was made and semithin and ultrathin sections were obtained and examined to show the ultrastructure of small intestine. The results revealed that X-ray irradiation resulting in loss of architecture and disarrangement of cells of the microvilli which have pale cytoplasm and degenerated nuclei with a reduction of mean villous height, mean crypt diameter and mean number of villi per cross section. Also electromicroscopic feature revealed lack of parallel arrangement of microvilli, loss of glycocalyx covering, desquamation of microvilli, vacoulation of apical part of the cells, dilatation of rough endoplasmic reticulum, and damage of mitochondrial cristae. In group of irradiated animals pretreated with melatonin [group three], these changes were improved and the intestinal mucosal structure was preserved. Administration of melatonin prior to irradiation can protect the intestine against X-rays destructive effects

effect of medroxyprogesterone acetate on the structure of adrenal cortex [zona fasciculata] of adult female albino rat. Light and electron microscopic studies

The injectable contraceptive medroxyprogesterone acetate [MPA] is an internationally established option of birth control. To evaluate the possible effects of MPA on the structure of zona fasciculata cells, the adrenals of forty adult female albino rats were used. The experimental animals were divided into four groups treated as follows: group I was kept as control, groups II and III were injected intramusculary with MPA for 2 and 4 months respectively. Animals of group IV were injected for 4 months and sacrificed one month after the last injection. Specimens from the adrenal gland were taken and processed for light and electron microscopic examination. It has been found that MPA caused an increase in the thickness of zona fasciculate and activation of the cells when administered for 2 months. The cells showed numerous lipid droplets, large number of mitochondria and prominent smooth endoplasmic reticulum. However, MPA administration for 4 months resulted in reduction in the thickness of zona fasciculata with degenerative changes in its cells. The cells appeared small and separated from each other and exhibited many lysosomes and intracellular vacuolar spaces. After withdrawal, most of the cells appeared more or less normal and few cells showed some structural changes. These findings indicated that MPA at first caused activation of fasciculata cells and increased steroidogenesis, but prolonged use of MPA induced inactivation and degenerative changes in these cells. However some of these changes were reversible on withdrawal of the drug. Therefore precaution and follow up must be considered with prescribing this drug for prolonged periods