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NERVE CELLS

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Originally appearing in Volume V19, Page 401 of the 1911 Encyclopedia Britannica.
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NERVE CELLS are unipolar, bipolar or multi-polar. Unipolar cells are found in the ganglia on the posterior roots of the See also:spinal nerves, and only give off an axon or See also:axis See also:cylinder See also:process; this, however, soon divides in a T-shaped manner, and all these cells were originally bipolar, though the See also:cell has grown away from its two axons (or, as they are often regarded, axon and dendrite), leaving a stalk joining it to them at right angles. Bipolar cells are found as an embryonic See also:stage of unipolar, though in See also:fish they persist in the spinal ganglia throughout See also:life. They are also some-times found in the sympathetic ganglia. Multi-polar cells are found in the See also:brain and See also:cord, and are best studied in the anterior horns of the See also:grey See also:matter of the latter, where they are nearly visible See also:Cunningham's See also:Text- to the naked See also:eye (see fig. 2). Of their many See also:Book of See also:Anatomy. processes only one is an axon, and it becomes fibre from a See also:Frog. other See also:fibres are called dendrites, and break up (After v.See also:Kolliker.) Into delicate branches some of which surround, but, it is generally believed, are not actually continuous with, neighbouring cells or their processes. It is known that the axons are made up of delicate fibrils, and it is thought by some observers that there is actual continuity between some of these and those of an adjacent neuron, as the See also:combination of a nerve' cell, its axon and dendrites, is called. The cells of Purkinje in the cerebellum show a particularly See also:rich arborization of dendrites (see BRAIN, fig. 7). Nerve cells have generally a large clear See also:nucleus.

End of Article: NERVE CELLS

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