Light microscopic demonstration of myoid fibres in the nervous system

Abstract

SUMMARY In 1968 Puszkin and co‐workers isolated from brain an actomyosin‐like protein which was not derived from the vascular system. Since corresponding myofibrils had not been described in histology, the tannic acid‐phosphomolybdic acid‐Levanol Fast Cyanine 5RN stain for myosin and related proteins was applied to methacarn‐fixed paraffin sections of human central nervous system (CNS) and peripheral nerve. Extensive meshworks of myoid fibres were found in the marginal layer and in white matter. Spider‐like cells containing myoid fibres were found in some areas of grey matter. Many axons of peripheral nerves were surrounded by myoid material, but myelin sheaths in CNS were apparently extracted by the fixative. Correlation of these observations with histochemical, electron microscopic and X‐ray diffraction data indicated similarity of the distribution of myoid fibres and fibrous astrocytes; the astrocyte fibres show the X‐ray diffraction pattern of a‐helical proteins. The myoid material in peripheral nerve is apparently associated with the myelin sheath. This pilot study suggests that the actomyosin‐like protein isolated from brain is probably derived from glia fibres which show the staining and X‐ray diffraction properties of proteins of the myosin‐fibrin group.