White matter, brain, human, Luxol fast blue—PAS ×350. the cortex, the cytoplasm of the cell is not distinguishable. Thus, they appear as naked nuclei in the bed of nerve processes. The neuropil is essentially a
This micrograph shows the outer portion of the white matter.
densely packed aggregation of nerve fibers and neuroglial cells.
The small round nuclei (NN) belong to neuroglial cells. As in
KEY BV, blood vessel Cap, capillary CC, cerebral cortex FC, fusiform cells GC, granule cells NN, neuroglial nuclei PC, pyramidal cells PM, pia mater V, vein WM, white matter
The cerebellum is a portion of the brain lying behind and below the cerebrum; it serves to coordinate both voluntary movements and muscle function in the maintenance of normal posture.
Cerebellum, brain, human, H&E ×40.
The cerebellar cortex has the same appearance regardless of which region is examined. In this low-magnification view of the cerebellum, the outermost layer, the molecular layer (Mol), is lightly stained with eosin. Under this is the granular layer (Gr), which stains intensely with hematoxylin. Together, these two layers constitute the cortex of the cerebellum. Deep in the granular layer is
Cerebellum, brain, human, H&E ×400.
At the junction between the molecular and granular layers are the extremely large flask-shaped cell bodies of the Purkinje cells (Pkj ). These cells are characteristic of the cerebellum. Each possesses numerous dendrites (D) that arborize in the molecular layer. The Purkinje cell has a single axon that is not usually evident in H&E sections. This nerve fiber represents the beginning of the outflow from the cerebellum. The figure shows relatively few neuron cell bodies, those of the basket cells (BC ), in the molecular layer; they are widely removed from each other and, at another region that stains lightly with H&E and, except for location, shows no distinctive histologic features. This is the white matter (WM ). As in the cerebrum, it contains nerve fibers, supporting neuroglial cells, and small blood vessels, but no neuronal cell bodies. The fibrous cover on the cerebellar surface is the pia mater (Pia). Cerebellar blood vessels (BV ) travel in this layer. (Shrinkage artifact has separated the pia mater from the cerebellar surface.) The rectangular area is shown at higher magnification in Figure on right.
best, show only a small amount of cytoplasm surrounding the nucleus. In contrast, the granular layer presents an overall spotted-blue appearance due to the staining of numerous small nuclei with hematoxylin. These small neurons, called granule cells, receive incoming impulses from other parts of the CNS and send axons into the molecular layer, where they branch in the form of a T, so that the axons contact the dendrites of several Purkinje cells and basket cells. Incoming (mossy) fibers contract granule cells in the lightly stained areas called glomeruli (arrows). Careful examination of the granular layer where it meets the molecular layer will reveal a group of nuclei (G ) that are larger than the nuclei of granule cells. These belong to Golgi type II cells.
Cerebellum, brain, human, silver stain ×40.