الفهرس 
Introduction
Anatomy of the brain in the ratOnly 14 pages are availabe for public view
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Abstract
This immunohistochemical study aimed to detect and localize the neural stem cells in brain of the rats at different postnatal ages. It may help in providing alternative sources of functional neural cells. Also, the application of these neural stem cells (NSCs) may serve as a new therapeutic modality for central nervous system disease.
The present study was conducted on 70 albino rats from postnatal ages. They were divided into seven age groups each group, formed of 10 albino rats as follow: Group1: at one day age, Group 2: at one week age , Group 3: at one month age , Group 4: at 3 month age, Group5: at 6 month age , Group 6: at one year age and Group 7: at two years age .
All groups of albino rats were subjected to: anesthesia by intraperitoneal injection of Phenobarbital (100mg/Kg b.wt). Fixation by 4% paraformaldehyde in phosphate buffered saline (pH adjusted to 7.4).The brain was dissected out for each group and immediately put into the same fixative over night at 4˚C and subsequently cut into transverse paraffin sections with an interval of (10-50 μm) , the section stained with hematoxylin and eosin for the general histological structure, and immunostaining by specific stem cell marker nestin and sox2. The slides were studied using light microscopy. Morphometrical studies were done to evaluate the density of the neural stem cells using computer based image analysis system. Finally, data were collected, revised, verified and analyzed statistically using SPSS statistical package version (15) by - One way ANOVAs test. -ST. Test. Pearson Correlation Coefficient (r)
In the sections stained with Nestin,the cell processes appeared well define as the antibody stained only cytoskeleton (cytoplasmic antigen). In contrast, SOX positive cells appeared rounded as it stained the nuclei only (nuclear antigen).
Positive cells appear rounded, bipolar or star-shaped according to the migratory capacitance. These cells appeared scattered or in aggregations.
Nestin stained cells showed significant changes regarding the morphology.Early in postnatal age life most cells appeared bipolar whil in later ages appeared multiple processes bearing with increase in the length and ramification of these processes as age advancing. Nestin/ sox2 positive cells could be detected in all studied groups.
The density of nestin/sox2 positive cells showed a high significant increase in early age groups (one day to sixth monthes) then gradually declined in late groups (1 year to 2 years). These stem cells were detected in the hippocampus, sub ventricular zone of lateral ventricle, and in cerebellum. Their density differs from one age group to others but present throughout life in all age groups. The stem cells present in the neonatal period and increase with age till reaching maximum density at 6th month, then decline with old age.
Density of positive cells differs being more prevalent in cerebellum compared to hippocampus and sub ventricular zone of the lateral ventricle. Also the density of positive cells was more in the hippocampus than sub ventricular zone of lateral ventricle. In hippocampus it present in all layers mainly granular layer of dentate gyrus. In the lateral ventricle positive cells present in the sub ventricular zone of the lateral ventricle. In the cerebellum apositive cells were present mainly in granular and Purkinje cell layers.
It is recommended to:
• Design further studies to differentiat the neural stem cells to different types and detection of the factors helping this differentiation.
• Study the methods of migration of neural stem cells and the factors helping this migration