小脳微細構造に関する研究
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Investigations performed on minute structures of the cerebellum in the albino rat by a modification of Bielschowsky's silver stain method have revealed the following findings: (1) All the fine branches of the Purkinje dendrite that run horizontally end free in the molecular layer. Each one of these fibrils terminates in an oese which the author has termed "osen Korperchen." Among the fibrils that have oese-shaped terminations are the fibrils given off from the Purkinje dendrite and the process of the basket cell, and the climbing fibers and horizontal fibers that run in the molecular layer. The fibrils given off from the dendrite, which climb perpendicularly in the molecular layer, reach the surface of the cerebellar cortex, with the ultimate branches ramifying in the form of an umbrella, and ending in the innermost membrane which covers the surface of the cortex. The axon of a Purkinje cell has only two or three short collaterals that end free in the granular layer. (2) The descending branches given off from a basket cell concern in the formation of a basket-like nest, the upper Part of which is formed of fibers originating in the axon of the basket cell, and the lower part of which is made up of fibers originating in the medulla. The delicate twigs given off from the fibers forming a basket-like nest have terminations in the form of oese, and connect with the Purkinje cell. (3) climbing fibers originating in the medulla climb upward, winding spirally about the Purkinje dendrites and their branches. There are other fibers which climb parallel to the dendrites and their branches. They could also be classified as climbing fibers. (4) Countless horizontal nerve fibers that run horizontally in the tholecular layer have been found to be the horizontal branches given off either from the nerve fibers that climb perpendicularly in the molecular layer or from the axons of basket cells. The perpendicular nerve fibers climb perpendicularly in the molecular layer, and reach the surface of the cortex. (5) The Fananas nouroglia cell occurs in the molecular. layer. It has a process which, being given off from the upperpole alone, climbs perpendicularly in the molecular layer, and resembles oligodendroglia in form and structure. Large than Hortegaglia, the Fananas cell would be of a special type of oligodendroglia. (6) New types of neuroglia cells have been identified in the molecular layer: the cell of type 1 which, resembling as it does the Fananas, cell, has a process which, being given off only from the lower pole, descends in the molecular layer; and the cell of type 2 is a small round cell which always surrounds the Purkinje cell in the molecular and granular layers, and which has radial processes, the end of which connect with the fibrils of the basket cell, The neuroglia cells of this type form satellites around the Purkinje cells. (7) There are epitherial neuroglia cells of Golgi, which are located between the Purkinje cells. They have linear or Y-shaped processes which climb perpendicularly in the molecular layer, and reach the surface of the cortex. Having collaterals, the process connects with the Purkinje dendrites, as well as with the processes of adjoining nerve cells of the same variety. (8) Granular cells are of two forms: the one consists of a small nucleus and a large amount of cytoplasm, while the other has a large nucleus and a small amount of cytoplasm. Between these granular cells, there are the lymphatic lumen, the accumulated colloidal granules, the dendrites of granular cells and the oeseshaped terminations of moss fibers. These elements are connected with one another. It would seem that the granular cell is a form of nerve cells producing secretions, and that the colloidal granule is its product which is to be absorbed into the lymphatic lumen. (9) The Golgi cells located directly beneath the Purkinje cells are bipolar cells which resemble the Purkinje cells, but those located elsewhere are all multipolar cells. (10) The three types of neuroglia cells-macroglia, oligodendroglia and Hortegaglia-occur in every layer of the cerebellum. It has been found that there are two varieties of macroglia, big and little, and that the latter includes those that are transitional in form from oligodendroglia. Macroglia forms glial little foot in the capillary wall. Direct cell division takes place in macroglia and oligodendrolia. It would seem that Hortegaglia, forming glial little foot in the capillary wall, is as ectodermal in origin as macroglia is.
- 千葉大学の論文