Search results
Results from the WOW.Com Content Network
Mesenchyme (/ ˈ m ɛ s ə n k aɪ m ˈ m iː z ən-/ [1]) is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. [2] [3] The interactions between mesenchyme and epithelium help to form nearly every organ in the developing embryo. [4]
Brain cells make up the functional tissue of the brain. The rest of the brain tissue is the structural stroma that includes connective tissue such as the meninges , blood vessels , and ducts. The two main types of cells in the brain are neurons , also known as nerve cells, and glial cells , also known as neuroglia. [ 1 ]
It is composed of dense fibrous tissue, and its inner surface is covered by flattened cells like those present on the surfaces of the pia mater and arachnoid mater. The dura mater is a sac that envelops the arachnoid mater and surrounds and supports the large dural sinuses carrying blood from the brain toward the heart.
The arachnoid mater covering the brain is referred to as the arachnoidea encephali, and the portion covering the spinal cord as the arachnoidea spinalis. The arachnoid and pia mater are sometimes considered as a single structure, the leptomeninx, or the plural version, leptomeninges ( lepto , from the Greek root meaning "thin" or "slender").
Thus, hand preference (which hand someone prefers to use) is also related to hemisphere lateralization. [citation needed] In some aspects, the hemispheres are asymmetrical; the right side is slightly bigger. There are higher levels of the neurotransmitter norepinephrine on the right and higher levels of dopamine on the left.
The left and right sides of the brain appear symmetrical, but they function asymmetrically. [113] For example, the counterpart of the left-hemisphere motor area controlling the right hand is the right-hemisphere area controlling the left hand. There are, however, several important exceptions, involving language and spatial cognition.
Most famous parts of the brain highlighted in different colours. The human brain anatomical regions are ordered following standard neuroanatomy hierarchies. Functional, connective, and developmental regions are listed in parentheses where appropriate.
The substantia nigra is a third colored component found in the brain that appears darker due to higher levels of melanin in dopaminergic neurons than its nearby areas. White matter can sometimes appear darker than grey matter on a microscope slide because of the type of stain used.