The Morphological Changes of Oligodendroglia During the Formation of Myelin Sheaths Golgi Study and Electron Microscopy

• Published in: Okajimas Folia Anatomica Japonica Vol. 50; no. 5; pp. 327 - 343
• Main Authors: Inoue, Yoshiro, Sugihara, Yoshihiro, Nakagawa, Shoji, Shimai, Kazuyo
• Format: Journal Article
• Language: English
• Published: Japan Editorial Board of Okajimas Folia Anatomica Japonica 1973
• Subjects: Animals; Chick Embryo; Chickens; Histological Techniques; Microscopy, Electron; Myelin Sheath; Neuroglia - cytology
• ISSN: 0030-154X; 1881-1736
• DOI: 10.2535/ofaj1936.50.5_327

In the brain of chick embryos and young chicks just after hatching the morphological changes of oligodendroglia during myelin formation were investigated with the Golgi method and the relationship between their changes in shape and myelin formation was discussed. It was inferred that an immature type of oligodendroglia sent out numerous thin processes, some tips of which might attach nearby neuronal axons, enclose them and elongate along them. The portions corresponding to the enclosing tongues was considered to be demonstrated as the various length of the tubular structures on the tips of the cytoplasmic processes by the Golgi method, since silver granules were precipitated as well in the outer and inner cytoplasmic tongue around the axon as in a cell body and cytoplasmic processes of oligodendroglia, which was demostrated by the electron microscopy of the Golgi stained materials. As the tub u lar structures became more elongated, the processes decreased in number, and as the myelin lamellae developed more densely, the tubular structures might be probably no longer silver-impregnated, to result in the characteristic silver-impregnated images of the mature oligodendroglia. From the findings of the arrangement of the tubular structures along an axon, internodal segments of a myelinated nerve fiber were apparently made by the plural oligodendroglia, and furthermore, single oligodendroglia seemed to be able to form two or more internodal segments along an axon. On the other hand, it was clear that an oligodendroglia was simultaneously associated with the formation of myelin sheaths of the plural axons (probably ten or so axons). It was presumed that the myelin lamellae developed in a spiral manner simultaneously with the elongation of the internodal length to reach the Ranvier's node, and then the spiral lamellae became much denser to complete the compact myelin sheaths.