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KMID : 0376219740110041375
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Chonnam Medical Journal
1974 Volume.11 No. 4 p.1375 ~ p.1393
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Electron Microscopic Studies on the Transfer of Tracer Substances by Rabbit Ependyma
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Abstract
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To investigate the transfer mechanism of the tracer materials by. the ependymal cells to the parenchyma of the brain, electron microscopic studies were made on the ependymal , and subependymal tissues of the lateral ventricle. of. the rabbit following, the administration. of ferritin or colloidal gold into the lumen of the lateral ventricle. - Results obtained were summarized as follows: 1.Ependymal cells furnished with the cilia and had the tight or open junctions at the luminal border of the intercellular space which was followed by the fascia adherens. Intercellular spaces in the basal region of the ependyma were generally wide but often had the zonulae occludente´s.
2. Twenty minutes after ferritin administration, ferritin particles penetrated into the intercellular space in significant amount and few of them reached to the basal region of the ependymal layer, although no ferritin was found in the Interspace of the zonulae occludentes. Ependymal cells contained some amount of ferritin particles in vesicles,´ vacuoles and multivesicular bodies, but free ferritin particles in the cytoplasm were very rarely found.
3. Three hours after ferritin administration, ferritin particles decreased in the intercellular space,near the luminal portion but were increased in the cytoplasm of the ependymal cell as well as in the subependymal parenchyma of the brain, where ferritin particles were seen in the basal lamina, endothelial cells and the lumen of the capillaries. In the glial cells, ferritin particles were abundant within the vesicular or vacuolar compartments. They were also found in the myelin lamellae and axoplasm of the myelinated nerve fibers.
4. Three hours after colloidal gold administration, no gold particles were noted in the ependymal cells, intercellular spaces or subependymal tissues.
From these results, it is suggested that intercellular spaces of the ependyma is the route for °the substances from the ventricular, fluid to the subependymal , parenchymal tissue or vice versa. Materials in the cerebrospinal fluid can be absorbed by the pinocytotic process of the ependymal and parenchymal cells and may. be digested in the lysosomes. Transfer or removal of the substances from the ventricular lumen may differ according to the substances, if the materials .re not removed by ependymal cells, they may take the route to the subarachnoid space.
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