الفهرس 
Review of Literature Structure of the Cerebellum
Phylogenetic and functional divisionsOnly 14 pages are availabe for public view
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Abstract
The present work investigated the effects of Diabetes mellitus on the structure of cerebellum of both male and female rats and the possible protective role of oral intake of melatonin.
Forty eight adult albino rats, twenty four males and twenty four females, were used in this study. Animals were divided into four groups. Rats in group I Were used as control. Animals in group II were given alloxan intraperitoneal in a dose of 150 mg/ Kg bodyweight to induce diabetes mellitus. Those in group III were given oral melatonin only in a dose of 10 mg/kg bodyweight per day. Rats in group IV were given oral melatonin after induction of diabetes. Each group was further subdivided into male and female subgroup. After two weeks at the end of experiment, animals were sacrificed; the cerebella were excised. Midsagittal serial sections of half of the cerebellum were cut at 7 μm thickness and stained with Haematoxylin and Eosin, Cresyl violet stain and Glial Fibrillar Acid Protein (GFAP). The other half of the cerebella were fixed immediately in 2.5 % glutaraldehyde in phosphate buffer for 3 hours. Fixed tissue samples were washed with phosphate buffer and post fixed in 1 % osmium tetra oxide. Semi thin sections one um thick were cut using L.K.B. ultra microtome, picked up on a gelatinized glass slides and stained with toluidine blue. All sections were examined and photographed with light microscope.
Ultrathin sections were cut with a diamond knife with L.K.B. ultra microtome and picked on uncoated 300-mesh copper grids, stained with ultrastainer using Uranyl acetate and lead citrate and examined with transmission electron microscope.
Morphometric studies were also done. The GFAP percentage areas were measured in the GFAP immunohistochemistry stained sections using digital photomicrographs taken at magnification of 400. The number of apparently normal Purkinje cells was counted in cresyl violet sections using digital photomicrographs taken at magnification of 400.
In the present study, histological sections of the cerebella from alloxan-induced diabetic rats generally showed intact arrangement of the three cortical layers. However, considerable degenerative changes were observed in the three layers. Purkinje cells were mostly affected; Most of them were distorted in shape with irregular darkly stained nuclei with wide areas of pericellular halo surrounding them. They were few and some of them had pyknotic nuclei. They were distorted in shape and contained ill defined Nissl granules in cresyl violet sections. Examination of the GFAP stained sections of diabetic rat cerebella showed a strong positive reaction of GFAP immunostaining for astrocytes cell bodies and dendrites in all layers of cerebellum. In semithin sections of cerebella of diabetic rats of both genders, there was multiplicity of the nerve fibers in the granular layer, that were small in size and variable in shape with different thickness of their myelin sheath .Some granule cells had darkly stained irregular nuclei. Examination of ultrathin sections of the cerebellar cortex of the diabetic groups revealed some shrunken Purkinje cells with darkly stained nuclei surrounded by a narrow rim of cytoplasm. Other Purkinje cells had large ill-defined darkly stained nuclei with an electron-dense cytoplasm contained hardly differentiated organelles.
In melatonin treated diabetic rats, The Purkinje cells were slightly reduced in number. They were arranged in one row, some of them regained their flask shape and apical cytoplasmic cones and pale nuclei. Some of them exhibited darker nuclei compared with those of the control group. There were free spaces or halos around Purkinje cells. In cresyl violet stained sections, the Purkinje cells were more or less normal in shape. The number of Purkinje is decreased compared to control group. Examination of the GFAP stained sections revealed fewer numbers of astrocytes with thin processes compared with diabetic group but more than that of the control group. Examination of semithin sections stained with toluidine blue revealed normally appeared Purkinje cells with their oval shape, pale nuclei, prominent nucleoli and apical cytoplasmic cones. Examination of ultrathin sections of the cerebellar cortex of melatonin treated rats revealed nearly normal ultrastructure of Purkinje cells with a euchromatic nucleus and a slightly electron-dense cytoplasm. The Purkinje cell regained its pyriform shape with apical cytoplasmic cone. Some Purkinje cells showed irregularity of the nuclear membrane. The cytoplasm of Purkinje cells were containing mitochondria that of nearly similar appearance to that of the control group with intact cristae. There were intact cisternae of rough endoplasmic reticulum.
There was no significant difference in number of Purkinje cells and GFAP percentage between diabetic male and diabetic female rats and also between Melatonin treated male rats and Melatonin treated female rats.