الفهرس 
Introduction
TelencephalonOnly 14 pages are availabe for public view
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Abstract
inhibitory interneurons. Tenascin R expression is being started by corpus striatum, at late embryonic stages. TN-R is also expressed by oligodendrocytes, immature astrocytes in the somatosensory cortex and at nodes of Ranvier in the central nervous system.
The present study was designed to detect the role of tenascin in the development of central nervous system of the rat embryos at different ages. Thirty (30) adult Albino rats (20 females and 10 males) were brought from animal house, Cairo faculty of medicine. Rats were housed in standard individual maternity cages under controlled temperature and humidity with free access to water and food. Mating of male and female rats were allowed (two females with one male in every cage) and females were checked for the presence of vaginal plugs each morning; which represents the day O of pregnancy (EO). Seventy (70) embryos of pregnant female rats were obtained after sacrifying female rats at different periods of pregnancy as the following and each group consisted of 10 embryos: Group1: at prenatal day (8); Group 2: at prenatal day (10); Group 3: at prenatal day (12); Group 4: at prenatal day (14); Group 5: at prenatal day (16); Group 6: at prenatal day (18) and Group 7: at prenatal day (20). The embryos are taken as a whole mount after extravasation of the internal organs of the abdomen and thorax, then they were put into paraffin blocks to be sectioned for immuno-histochemical staining. Longitudinal sections were incubated with primary antibody; tenascin antibody. These sections were incubated with biotinylated anti-mouse secondary antibody followed by the avidin–biotin complex (ABC) method. Finally, the sections were visualized with 3, 3-diaminobenzidine (DAB). The slides were studied using light microscopy and subjected to morphometrical and Statistical analysis.
The results of the present study revealed the following
Tenascin is upregulated in ventricular zones with the age of 10 days, 12 days, and 14 prenatal; the maximal increase was in 14 days prenatal; In subventricular zone, tenascin expressed only in 14 and 16 days prenatal with the level increased in 16 more than 14 days prenatal; In cerebral cortex, tenascin was expressed at 16, 18 and 20 days prenatal. The maximal increase was in 20 days prenatal; In corpus striatum, it was expressed in 14 and 16 days prenatal, and increased in 16 days more than 14 days prenatal; In hippocampus, it was expressed in 18 and 20 days prenatal, and increased in 20 days more than 18 days prenatal; In spinal cord, tenascin expression was negative in 12 and 14 days prenatal and positive in 16, 18 and 20 days prenatal. The maximal expression was in 20 days prenatal;T he main findings of the present study showed that, tenascin were upregulated with age in cerebral cortex, spinal cord, ventricular zone, subventricular zone, corpus striatum and hippocampus. These results indicate that, tenascin may play a pivotal role in CNS development.