Effect of long-term exposure to su-light on the ultrastructure of epidermal melanin unit of the human skin

The aim of the present work was to study the ultrastructural features of the melanocytes and related keratinocytes in chronically sun- exposed skin. 10 fair-skinned adult males, whose occupation required long exposure to sun light were chosen for this study. Chronic exposure to sun light enhanced the proliferative activity of the epidermal melanocytes accompanied by increased melanin content, variable dendritic morphology and appearance of numerous pinocytotic vesicles and vacuoles. Moreover, migration of melanocytes were demonstrated in the sun-exposed skin into suprabasal and subbasal [dermal] positions. Groups of melanocytes were demonstrated in the superficial part of the dermis denoting nest formation. In addition, chronic exposure to sun light induced marked proliferation of the epidermal keratinocytes leading to increased epidermal thickness. Also, their pigment content was increased due to enhanced melanin transfer from the nearby melanocytes. Moreover, there was concentric condensation of the excess melanin pigments and cytoplasmic tonofilaments around their nuclei forming a shield to protect the nuclear DNA against the harmful effect of solar ultraviolet rays

Histological changes of the remaining live donor's kidney in rat. A light microscopic, electron microscopic and morphometric study

Twenty adult male albino rats were used in this study. The results revealed a significant increase in all the parameters measured in the remaining kidney after 2 months. Their weight was increased by 160%, the glomerular surface area increased by 140%. The proximal tubules showed an increase of their diameter by 27% and the height of their lining cells increased by 30%. With PAS technique, focal and diffuse thickenings of glomerular basement membrane were evident together with increased mesangium. However, hydropic degeneration and tubular necrosis were detected in many tubular cells after 2 months. With PAS, their basement membranes showed focal thickenings and their brush borders were thin and interrupted. The electronmicroscopic examination of the renal cortex after one month displayed focal thickenings in the glomerular basement membranes mainly at lamina densa. Marked narrowing of the glomerular capillary lumina by the proliferating endothelium and mesangium was observed. Mitochondria were swollen, vacuolated and lost their parallel alignment, endoplasmic reticulum appeared swollen. Lysosmes and pinocytotic vesicles were increased

Histological and histochemical changes in the kidneys of albino rats after injection of bleomycin sulphate [Blenoxane]

The toxic effects of bleomycin sulfate [Blenoxane] on the kidney of adult male albino rats were investigated. Atrophy and collapse of the renal corpuscles were noticed and confirmed with morphometric study showing significant reduction in the surface area of the renal glomeruli. The convoluted tubules revealed vacuolation of the cytoplasm of the proximal segment and dilatation of the distal segment with a decrease in the height of the lining epithelium. The nuclear changes including pyknosis and karylosis started 3 days after injection of the drug and were prominent in the one week group. DNA staining confirmed the reduction in its amount and density in the experimental groups. The basement membranes of the renal tubules and corpuscles were interrupted in some areas and wavy with irregular thickening in other ones. The PAS positive brush border of the proximal convoluted tubules was partly deficient in some cortical regions. However, the mitochondrial reaction was decreased in the basal parts of the renal tubules

Histological and histochemical studies on the effect of colchicine on the liver of the albino rat

The effect of long term administration of a chronic daily dose of colchicine [1 mg and 6 mg/kg body weight] on the liver of the albino rat has been investigated. Collagenous and reticular fibres of the stroma were disrupted. Some empty spaces appeared in the portal tract. Lymphocytic and mononuclear cellular infiltration were also observed in the portal tracts as well as near central veins. Large and small vacuoles were seen inside hepatocytes in the peripheral zones of the hepatic lobules. Golgi body was enlarged in size. Depletion of fat droplets and glycogen granules was a marked feature. However, at the end of experiment, there was an apparent regeneration of the collagenous and reticular fibres with a decrease in size of the Golgi body. The mononuclear and lymphocytic infiltration were also diminished. Reappearance of glycogen granules in most of the hepatic lobules was noticed but the depletion of fat droplets was still persistent. In Hx. and E. stained sections, hepatocytes were apparently similar to those of the control group