THE FINE STRUCTURE OF NEURONS

TLDR

The Nissl substance of neurons consists of endoplasmic reticulum with varying orientation and punctate granules, while the surrounding cytoplasm contains numerous mitochondria, lipid inclusions, and fine filaments. Thin sections of neurons from various ganglia and brain regions were examined by electron microscopy, revealing a second membrane system with shallower, tightly packed cisternae lacking granules. Intermediate forms between the two membranous systems were observed. Footnote markers 1–4 are included.

Abstract

1. Thin sections of representative neurons from intramural, sympathetic and dorsal root ganglia, medulla oblongata, and cerebellar cortex were studied with the aid of the electron microscope. 2. The Nissl substance of these neurons consists of masses of endoplasmic reticulum showing various degrees of orientation; upon and between the cisternae, tubules, and vesicles of the reticulum lie clusters of punctate granules, 10 to 30 mmicro in diameter. 3. A second system of membranes can be distinguished from the endoplasmic reticulum of the Nissl bodies by shallower and more tightly packed cisternae and by absence of granules. Intermediate forms between the two membranous systems have been found. 4. The cytoplasm between Nissl bodies contains numerous mitochondria, rounded lipid inclusions, and fine filaments.