Neuroanatomy: Grey and White Matter, Spinal Cord, and Nerve Structures

What is the appearance of grey matter in life and why?

Grey matter appears reddish brown due to the high density of blood vessels needed to support neuronal metabolism.

Where are neuron cell bodies located in the brain?

Neuron cell bodies are located in grey matter.

What forms white matter in the brain?

White matter is formed by axons bundled into tracts, which are white due to low blood vessel density and high fat content of myelin.

What is the significance of Nissl substance in neurons?

Nissl substance, visible in the cytoplasm, indicates the presence of rough endoplasmic reticulum and is used to identify neurons.

What are the characteristics of astrocytes in grey matter?

Astrocytes have large, round nuclei with dispersed chromatin, but their cytoplasm and projections are not visible in H&E stained sections.

How can oligodendrocytes be distinguished from microglia?

Oligodendrocytes have small, round, hyperchromatic nuclei and are located in grey matter, while microglia are not distinguishable in H&E sections.

What is the primary cell type in white matter?

Oligodendrocytes are the predominant cell type in white matter.

Describe the organization of the cerebellar cortex.

The cerebellar cortex has a molecular layer with dendrites of Purkinje cells, a layer of Purkinje cells, and an internal granular cell layer with densely packed granular neurons.

How is the organization of grey and white matter different in the spinal cord compared to the brain?

In the spinal cord, white matter is on the surface and grey matter is on the interior.

What are the three horns of grey matter in the spinal cord and their functions?

Ventral horn (motor neuron cell bodies), lateral horn (sympathetic neuron cell bodies), dorsal horn (neurons receiving somatosensory information).

What is the role of Schwann cells in the peripheral nervous system?

Schwann cells myelinate axon segments and produce collagen on the side opposite the axon.

What is the structure that surrounds individual axons and Schwann cells?

Endoneurium is the connective tissue that separates individual axons and their Schwann cells.

What is the function of perineurium?

Perineurium bundles groups of axons into larger units.

What is the outer sheath of a peripheral nerve called?

The outer sheath is referred to as the epineurium.

How do sympathetic and parasympathetic neurons differ in their synapse locations?

Sympathetic neurons synapse with discrete ganglion cell neurons, while parasympathetic neurons synapse with neurons embedded in the target organ.

What is a plexus in the context of the autonomic nervous system?

A plexus is an aggregate of neurons located in the muscle tunics and submucosa of the intestine.

What is the significance of the distance between nodes of Ranvier?

The distance between nodes of Ranvier helps distinguish myelinated segments of axons.

What type of neurons are found in dorsal root ganglia?

Dorsal root ganglion neuronal cell bodies are large and correspond to the length of sensory axons.

What is the function of sustentacular cells in dorsal root ganglia?

Sustentacular cells support dorsal root ganglion neurons and have a function similar to astrocytes.

What happens to axons during surgical manipulation of nerves?

Manipulating the epineurium with surrounding fat prevents axons from being crushed.

What is the histological appearance of white matter in the spinal cord?

The histological appearance is similar to that in the forebrain, with axons running parallel to one another.

What is the approximate thickness of tissue sections used to study grey and white matter?

Tissue sections are approximately 8-10 microns thick.

What structures can be observed in thick sections stained with silver?

Thick sections stained with silver can reveal dendrites and axons.

What is the role of the axon hillock in neurons?

The axon hillock is where the base of an axon emerges from the cell body.