Page 365 - Atlas of Histology with Functional Correlations

MORPHOLOGY AND TYPES OF

NEURONS IN THE CENTRAL NERVOUS

SYSTEM (CNS)

Neurons are structural and functional units of the CNS that receive and

conduct impulses
Consist of soma (cell body), dendrites, and axons
Three main neuron types are multipolar, bipolar, and unipolar

Multipolar are most common and include all motor neurons and interneurons
of the CNS
Multipolar neurons contain numerous dendrites and a single axon
Bipolar neurons are sensory and found in the eyes, nose, and ears
Bipolar neurons contain a single dendrite and a single axon

Unipolar neurons are found in sensory ganglia and dorsal root ganglia of
spinal and cranial nerves
Unipolar neurons exhibit one process from the cell body that divides into two

axonal branches
One unipolar branch continues to the CNS, the other to the peripheries
Interneurons found in the CNS integrate and coordinate stimuli between
sensory, motor, and other interneurons

MYELIN SHEATH AND MYELINATION

OF AXONS

Specialized cells wrap around axons to form lipid-rich, insulating myelin
sheath

Myelin sheath extends along the length of the axon to its terminal branches
Gaps between myelin sheaths are nodes of Ranvier
In the PNS, Schwann cells myelinate individual axons and envelope
unmyelinated axons

Islands of Schwann cell cytoplasm form Schmidt-Lanterman incisures or
clefts
Unmyelinated axons do not show nodes of Ranvier
In the CNS, processes from single neuroglial oligodendrocyte cells extend

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