XVI.—Electron Microscopic Studies of Spinal Ganglion Cells

Abstract

Synopsis Thin sections of the spinal ganglion of the rat were cut and examined with the electron microscope. Two main types of nerve cell are described. Type A with equal electron density of nucleus and cytoplasm. The cytoplasm contains large aggregates of Nissl's substance discretely scattered throughout the cell, mitochondria and osmophilic granules. Type B with a “light” nucleus and a “dark” cytoplasm. The cytoplasm is closely packed and homogeneous so that it is difficult to separate out the various cytoplasmic elements. There is a well-marked nuclear membrane about 500 Å thick and characteristic strawberry nucleolus. The capsular cells are closely applied to the nerve cell with no intervening boundaries. A system of cytoplasmic filaments—the “endoplasmic reticulum”—is present in the intercellular regions. There are nerve fibres with lamellated myelin sheath, axolemma, Schwann cells and Schwann membrane.