Human brain tissue can appear in different colors depending on specific regions and components. However, there are three main colors that are most commonly associated with brain matter: white/beige, grey, and red.
Quick Answer
The outer brain tissue is often whitish/beige in color from myelin, the insulating fatty tissue that surrounds axons and allows for faster transmission of electrical signals. The cerebrum is composed of grey matter which contains cell bodies, dendrites, unmyelinated axons, glia, capillaries, and synapses. Deep structures like the basal ganglia and substantia nigra are also grey. Finally, a reddish/pink color comes from blood vessels and capillaries throughout the brain.
White/Beige Brain Matter
The whitish or beige color of some brain matter is primarily due to myelin, which is a fatty substance that surrounds the axons of many neurons. Myelin acts as an insulator that allows electrical signals to transmit faster and more efficiently along axons.
Myelinated axons make up the white matter of the brain and spinal cord. White matter contains bundles of myelinated nerve cell projections (axons) that connect various grey matter areas of the brain to each other and to the spinal cord. Myelin gives white matter its distinctive white or beige color.
The major areas of the brain considered white matter include:
- The corpus callosum
- Corona radiata
- Internal capsule
- Optic tract
- Cerebral peduncles
- Fornix
These regions contain high concentrations of myelinated axons interconnecting grey matter areas with distant regions of the brain and spinal cord. The white color helps differentiate these regions from the nearby grey matter during anatomical dissections.
Grey Matter
Grey matter in the brain consists primarily of neuronal cell bodies, their dendrites, unmyelinated axons, glial cells, blood vessels, and capillaries. This gives grey matter an overall greyish appearance in color.
The grey matter makes up the outermost cerebral cortex of the brain as well as central structures like the basal ganglia, hippocampus, and substantia nigra.
Some of the key functions linked to the cerebral cortex grey matter include:
- Higher cognitive functions like speech and decision making
- Sensory perception
- Motor control
- Spatial reasoning
- Conscious thought
The basal ganglia grey matter is important for regulating movement and coordinating muscle activity. The hippocampus deals with memory formation and storage. And the substantia nigra helps control voluntary movements.
Red Color in Brain Matter
While grey and white matter make up the majority of brain tissue, a reddish or pinkish color can also be seen in certain areas. This reddish color comes from the profuse blood vessels and capillaries that nourish the metabolically active neurons of the brain.
The high concentration of blood vessels gives some brain structures a distinctly reddish appearance, such as:
- The pons
- Medulla oblongata
- Midbrain
- Choroid plexus
The choroid plexus in particular has a deeply red appearance. This structure is located in the ventricles of the brain and is responsible for producing cerebrospinal fluid (CSF). The choroid plexus contains dense networks of blood vessels and capillaries that filter blood and remove wastes to produce CSF. This gives it a deep reddish-purple color.
| Brain Region | Color | Cause of Color |
|---|---|---|
| Corpus callosum | White/beige | Myelinated axons |
| Cerebral cortex | Grey | Neuronal cell bodies, dendrites, glia, capillaries |
| Basal ganglia | Grey | Nuclei, neuronal cell bodies |
| Choroid plexus | Red | Dense capillary networks |
Conclusion
In summary, the predominant colors seen in brain matter are:
– White/beige from myelinated axons in white matter tracts
– Grey from neuronal cell bodies, dendrites, glia, and capillaries making up grey matter regions
– Red from the dense vasculature of structures like the choroid plexus
Knowing the source of these different colors in the brain provides insight into the various components and tissue types that enable this remarkably complex organ to regulate all aspects of human thought, emotion, and behavior. Proper functioning depends on the interconnected network of white matter, grey matter, and blood vessels that give the brain its distinctive coloration.