Neuroglial cells

Neruoglial cells

 Neuroglial cells are found only within the tissues of the brain and spinal cord where they several times more numerous than neurons. They fill spaces, support neurons and generally hold organs together. Unlike neurons, Neuroglial cells are capable of reproduction. Thus it is not surprising that they are sometimes responsible for the development of tumors in the brain or spinal cord, neurons seldom if ever from tumors.

Although myelin begins to form on nerve fibers during the fourteenth week of development, many of the nerve fibers in a newborn infant are not completely myelinated. Consequently, the nervous system is unable to function as effectively as that of an older child or adult. An infant’s responses to stimuli are, therefore coarse and undifferentiated and may involve its whole body essentially all myelinated fibers have begun to develop sheaths by the time a child begins to walk. Myelinated continues into adolescence.  

Although neuroglial cells vary greatly in their structure and functions, the following types –

Astrocytes

As their name implies, astrocytes are star-shaped cells. They are commonly found between nerve tissues and blood vessels, where they seem to function in providing structural support and in holding parts together by means of numerous cellular processes. They may also function to remove cellular debris and seal off damages areas following injuries to the central nervous system.

Oligodendrocytes 

Oligodendrocytes resemble astrocytes but are smaller and have fewer processes. They are commonly arranged in row along nerve fibers, and they function in the formation of myelin within the brain and spinal cord. 

Microglia

Microglial cells are relatively small and have fewer processes than other types of Neuroglial cells. These cells are scattered throughout the central nervous system where they help support neurons and are able to phagocytosis bacterial cells and cellular debris. They usually increase in number whenever the brain or spinal cord is inflamed because of injury or disease.

Ependyma

Ependymal cells are cuboidal or columnar in shape and may have cilia. They form an epithelia like membrane that is one cell thick and covers the following: the inside of spaces within the brain, called ventricles; the inside of the central canal that extends downward through the spinal cord; the specialized capillaries, called choroid plexuses, that are associated with the ventricles of the brain.