Glial cells, referred to as glial cells, are widely distributed in the central and peripheral nervous systems. Normal staining can only show the nucleus, and special silver staining can show the overall morphology of glial cells. Generally speaking, glial cells are smaller than nerve cells and have many irregular protrusions, the number of which is about ten times that of nerve cells. Most of them are distributed around cell bodies, processes and central nervous capillaries. Glial cells are supportive, nutritious and nutritious.

Glial cells in the central nervous system

1. Astrocytes are the largest type of glial cells. Its cell body is star-shaped, its nucleus is round or oval, and its staining is shallow. There are interwoven glial filaments in the cytoplasm. Many radial protrusions extend from the cell body, and some protrusions expand at the ends to form terminal feet, which adhere to or extend to the basement membrane of capillaries.

Glial cells can be divided into two types according to their distribution and structure.

(1) protoplasmic astrocytes: distributed in the gray matter of the central nervous system, surrounding the nerve cell body and its processes. Protoplasmic astrocytes have irregular processes, many short and curved branches, and their surfaces are not smooth. There are almost no glial fibers in the cytoplasm.

(2) Fibrous astrocytes: distributed in white matter and located between nerve fibers. Its protrusions are radial, slender and straight, with few branches and smooth surface. There are many interwoven fibers in the cytoplasm, and its ultrastructure is a kind of intermediate filament, which contains glial fibrillary acidic protein GFAP.

Astrocytes contain high concentration of K+ and can absorb some neurotransmitters (such as γ -aminobutyric acid). They affect the functional activities of neurons by regulating the concentration of K+ and neurotransmitters in intercellular space. Therefore, astrocytes play an important role in maintaining the stability of nerve cell microenvironment and regulating metabolic process. When the central nervous system is damaged, astrocytes will rapidly divide and proliferate, forming glial scars for repair.