Abstract

Performing an insulator function, the myelin sheath covers the axon, which is involved in conducting a nerve impulse. In the course of some research, great attention was paid to the relationship between the thickness of myelin sheath of the axon and its diameter and there were the statements of contradictory opinions. The purpose of the study is evaluation of the ratio of the thickness of myelin sheath of the axon to its diameter in nervous fibers of the musculocutaneous nerve in the prenatal ontogenesis. The pieces of the musculocutaneous nerve in 6 - 9 month old fruits a length of 63 mm and a length of 10 mm were got. The principles of the structure of myelinated fiber for all stages of prenatal ontogenesis are the same and in a full-term newborn the growth of common myelinated fiber occurs due to thickening of the myelin sheath and the growth of the axial cylinder. Between of the thickness of the myelin sheath and the diameter of the axial cylinder there is a straight line correlative relationship. In some cases, there are discrepancies in the general pattern: fibers with a thin myelin sheath have axons with large diameters or vice versa. This is a characteristic feature of the fibers in the earlier stages of the process of myelination and associated with preservation of cytoplasmic structures between the layers of lipoprotein plates.

Keywords: Musculo-Cutaneous Nerve; Axon; Myelin Sheath

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