Spinal Cord:
Development (Page 2 of 2)


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Alar plate (yellow) - Cell bodies in the alar plate form nuclei which constitute the dorsal gray horn (or columns) of afferent neurons that extend the length of the cord. Dendrites of neurons in the alar plate receive and relay incoming general somatic and general visceral sensory (GSA & GVA) information from axons of the pseudounipolar neurons located in the dorsal root ganglion and carried to the cord in dorsal roots of spinal nerves.

Basal plate (red) - Cell bodies here form the uninterrupted
ventral gray horn (or columns) of efferent neurons that extend the length of the cord. Axons of these neurons project general somatic efferent motor fibers to skeletal muscle and form the ventral roots of the spinal nerves. Intermediate gray horn of the basal plate is present in a more limited portion of the cord. In the thoracic segments, lumbar segments L1 - L3, and sacral segments S2 - S4 of the cord a lateral or (intermediate) gray horn is present at the junction of alar and basal plates. Cells here provide the first of 2 neurons general visceral efferent fibers that supply smooth muscle and glands. Axons of these cells exit the cord via the ventral roots.

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