Page 94 - Headlines Histology2024_Neat

Non-myelinated nerve fibers
• One or more nerve fibers become longitudinally invaginated into the
cytoplasm of the Schwann cell.
• Each fiber is embedded in a groove in the Schwann cell cytoplasm. A large
Schwann cell may invest up to 20 or mare axons.
• The lips of the grooves fuse with each other forming the mesaxon. The
conduction velocity is lower than that for myelinated nerve fibers.

Ganglia

• Ganglia are discrete aggregations of neuron cell bodies located outside the
CNS. There are two types of ganglia: cranio-spinal and autonomic ganglia.

Craniospinal (sensory) ganglia
• They are fusiform in shape and surrounded by a connective tissue capsule
of collagenous and reticular fibers.
• The neurons are pseudounipolar. Each cell has a single process that divides
into two branches. One branch passes into the spinal nerve where it ends in
a receptor organ. The other branch passes inward to reach the CNS. Both
branches are myelinated.
• The cell bodies are spherical with different sizes ranging from 15-120 ?m.
• The nuclei are spherical, large, euchromatic with prominent nucleoli and are
centrally located. The cytoplasm contains basophilic granules. The cells are
arranged in clusters that are located peripherally.
• A complete layer of flattened satellite cells that provide structural and
metabolic support surrounds each cell body.
• Blood vessels, dendrites and bundles of axons are found between the
ganglionic cells. The nerve fibers are thick and myelinated.

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