📝 STANDARD DESCRIPTION:
CEREBRUM: Outer gray-matter cortex containing neuronal cell bodies, neuropil and glia surrounds a white-matter core of myelinated axons. The neocortex is conventionally organized into six layers, although their prominence varies by region and species.
CEREBELLUM: Cortex has three layers: outer molecular layer, a single row of Purkinje-cell bodies, and an inner densely cellular granular layer. White matter forms the medulla and branches into the folia.
SPINAL CORD: Central H-shaped gray matter surrounds the ependyma-lined central canal; dorsal horns are principally sensory and ventral horns contain somatic motor neurons. White matter is peripheral and organized into funiculi.
📚 DETAILED DESCRIPTION:
MENINGES: Dura mater is dense connective tissue; arachnoid forms the boundary of the CSF-filled subarachnoid space; pia closely follows the CNS surface and carries vessels.
CEREBRAL CORTEX: Neocortical layers are molecular, external granular, external pyramidal, internal granular, internal pyramidal and multiform. Pyramidal neurons are projection neurons; astrocytes, oligodendrocytes and microglia occupy the neuropil.
CEREBELLAR CIRCUIT: Purkinje cells provide the sole output of the cerebellar cortex. Granule-cell axons form parallel fibers in the molecular layer; climbing and mossy fibers are major afferent systems.
SPINAL CORD: The intermediolateral autonomic region is prominent in species-dependent thoracolumbar segments. Ascending and descending tracts occupy defined white-matter funiculi. Brain and spinal-cord capillaries possess endothelial tight junctions that form the blood-brain barrier, supported by pericytes, basement membrane and astrocytic end-feet.
// COMPARATIVE ANALYSIS
| DOMESTIC MAMMALS |
Cortical thickness, gyrification, tract proportions and prominence of individual nuclei vary by species and breed; use species-appropriate sections for identification. |
| BIRD |
Avian pallial organization is nuclear rather than a mammalian six-layered neocortex, while cerebellar cortical layering remains molecular, Purkinje and granular. |
CLINICAL RELEVANCE
Selective neuronal necrosis, demyelination, gliosis and Wallerian degeneration have distinct microscopic patterns. Purkinje-cell loss is important in several inherited and toxic cerebellar disorders; spinal-cord lesion interpretation requires level, gray/white-matter distribution and tract involvement.
