Difference Between White Matter and Gray Matter

Both white matter and gray matter are terms that relate with the cells of the brain. A cross section of a brain will show these cells in their respective colours, and they are so named as white and gray matter. However, the two types of brain tissues become white and gray after being dipped in preservatives as the live colours are slightly different with the presence of blood. Gray and white matters are the two main types of brain cells and the functions of these vary from each other. Mainly, the processed signals by gray matter are being passed through white matter inside the brain.

White Matter

White matter is one of the two components of the brain that coordinate different regions of the brain. It is said that white matter of the brain is equivalent to the cables of a computer network. Even though the tissue is named as white, the live colour is pinkish white due to the presence of blood. The usual preservative, formaldehyde, makes the white matter to be white. Although it is stated here that white matter is present in the brain, there are also white matter tissues in other parts of the body associated with the nervous system such as the spinal cord, blood…etc.

White matter contains both glial cells and long axons that are often myelinated. The dendrites are absent in the cerebral and spinal white matter, but there are no neuronal cell bodies. The majority (60%) of the brain is composed of this issue, which is very important to convey pulses between regions of the brain. The quantifying of white matter is mainly done by considering the total length of the composed neurones. The total length of white matter in a male is more than 175,000 kilometres while a female has almost 150,000 kilometres long white matter cells at the age of 20 years. As the person gets old, this length lessens at the rate of 10% each year averagely. There are three major tracts or bundles of white matter based on the regions that they connect; they are known as Projection (connect vertically between higher and lower parts), Commissural (connect between the two cerebral hemispheres), and Associate (connect different regions of the same cerebral hemisphere).

Gray Matter (Grey Matter)

Gray matter is the most important component of the nervous system that is composed of regions of the brain responsible for sensory perception, memory, emotions, speech, and for almost all the muscle control. Gray matter is composed of neuronal cell bodies, glial cells, and capillaries. However, the presence of the nuropil, which is composed of unmyelinated axons and dendrites, is very important to notice. It would also be important to state that most of the neurones are myelinated in gray matter except in the nuropil. The live gray matter is mainly brownish-grey in colour due to the presence of blood capillaries and neuronal cell bodies. It is very difficult to understand the mechanisms of sensory processes taking place in different regions of gray matter, yet the scientists have identified the main regions involved in hearing, seeing, muscle controlling, thinking, and speaking. Therefore, gray matter has been sometimes referred as a set of computers with different specialities.

What is the difference between White Matter and Gray Matter?

• The basic colourations of both tissues have been the basis for the naming, and their colours can be considered to distinguish the two.

• Gray matter forms the processing units of sensory function while white matter forms the connections among gray matter units.

• The white matter is slightly more prominent (60%) than gray matter (40%) in the quantity.

• Cells of the white matter are longer than gray matter cells.

• The total length of white matter lessens with age, but gray matter does not dwindle significantly.