My Favourite Cell: Schwann Cells

My Favourite Cell: Schwann Cells

Introduction

A nerve is composed of several nerve fibres. Each fibre comprises a coated axon Schwann cells. The majority of neurons are between axon and cell Schwann sheathmyelin , which is produced by the same Schwann cell. Such fibres are called myelin. Other fibres have the sheath of myelin and deep grooves remain within Schwann cell.Schwann cells originate from the neural crest and accompanying axons during growth, forming the sheath that covers all PNS axons from the initial segment to their terminations. They are essential for the structural and functional integrity of the axon. Schwann cell is a glial cell type surrounding the axons of neurons, forming the myelin sheath. Schwann cells are present from birth of the neuron, and accompany it throughout its development. The close relationship being the neuron and the Schwann cell is given from its origins in the embryonic tissue. This type of glial cell plays a fundamental role in guiding axon growth correctly.

In contrast, when the axon diameter is large, these cells form the myelin sheath. This sheath is formed by winding around the axon of the multilayer membrane of the Schwann cell, spiral. All peripheral nervous system axons are myelinated by these cells, from inception to its termination (Bampton, 2001). Among a Schwann cell and the adjacent, there remains a small portion without myelinate axons, each of the remaining points without myelinate axons, are called nodes of Ranvier.

Schwann cells act as an electrical insulator, by myelin. This insulation surrounding the axon, cause the electric signal to traverse without losing the intensity which occurs facilitating called saltatory conduction. Schwann cells also help to guide the growth of axons and regeneration of the lesions of the peripheral axons.

Discussion

Schwann cells are derived from a structure called the neural crest, which forms above the neural tube during embryonic development. When in contact with axons, neural crest cells differentiate into Schwann cell precursor. They then become immature Schwann cells, while surrounding axons dozens of both. They can then become myelin santé Schwann cells and protect a single axon, or then become non-myelinating Schwann cells and axons surround several small diameter. This is determined by the diameter of axons with whom they are in contact. Axons broadest induce differentiation into Schwann cell pro-myélinisante through a molecular signal, whereas small diameter axons do not emit enough signal to induce such differentiation. Similarly, the thickness of the myelin sheath is proportional to the diameter of the axon (Jessen, 1999).

A major function of Schwann cells is creating the myelin sheath that allows the nerve impulse which is transmitted along the axon without loss in signal intensity, producing the so-called salutatory conduction. This means that the action potential is played only at the nodes of Ranvier, giving the feeling that the signal jumps from one node to the next, speeding up the transmission of nerve impulses without increasing the diameter of the axon. Furthermore, Schwann cells are involved in the processes of growth and repair of lesions in ...