gray matter

…a convoluted (wrinkled) layer of gray matter. The degree of convolution is partly dependent on the size of the body. Small mammals (e.g., lesser anteater, marmoset) generally have smooth brains, and large mammals (e.g., whale, elephant, dolphin) generally have highly convoluted ones.

…and an outer cortex of gray matter. The cerebral cortex is responsible for integrating sensory impulses, directing motor activity, and controlling higher intellectual functions. The human cortex is several centimetres thick and has a surface area of about 2,000 square cm (310 square inches), largely because of an elaborate series…

The superficial gray cortex is acquired by the migration of immature nerve cells, or neuroblasts, from their primary intermediate position in the neural wall. The diencephalon is preponderantly gray substance, but its roof buds off the pineal gland, which is not nervous tissue, and its floor sprouts…

… (white matter) and unmyelinated (gray matter) nerve fibres, and, similar to other structures in the brainstem, the white matter of the medulla, rather than lying beneath the gray matter, is intermingled with the latter, giving rise to part of the reticular formation (a network of interconnected neuron clusters within…

…and neuroglia predominate are called gray matter; areas in which myelinated neurons dominate are called white matter. Efferent, or motor, nerve fibres carry impulses away from the central nervous system; afferent, or sensory, fibres carry impulses toward the central nervous system. Visceral fibres innervate the viscera such as the heart…

The gray matter forms three pairs of horns throughout most of the spinal cord: (1) the dorsal horns, composed of sensory neurons, (2) the lateral horns, well defined in thoracic segments and composed of visceral neurons, and (3) the ventral horns, composed of motor neurons. The…