Distribution and ultrastructure of ventral root afferents to lamina I of the cat sacral spinal cord.
Following ventral root injury-filling with horseradish peroxidase at sacral spinal levels S1, S2, and S3, small fascicles of axons can be observed to enter the ventral portion of lamina I and arborize primarily in the dorsolateral region just medial to the tract of Lissauer (TL). Some axons enter the TL and turn in a rostrocaudal direction. Labeled axons studied by electron microscopy are both myelinated and unmyelinated, and terminals in lamina I contain round clear, and dense cored vesicles and contact smaller diameter dendrites and vesicle-containing elements. The concentration of these putative ventral root afferents appears to be largest in the S2 segment, with smaller numbers found within S1 and S3.
D000818:Animals; D002415:Cats; D008854:Microscopy, Electron; D009475:Neurons, Afferent / Q000166:cytology; D013116:Spinal Cord / Q000166:cytology* / Q000648:ultrastructure; D013126:Spinal Nerve Roots / Q000166:cytology* / Q000648:ultrastructure