Caspr reveals an aggregation of nodes and flanking node free zones at the rat trigeminal sensory root and dorsal root entry zones.
The sensory root entry zone demarcates the transition from the peripheral nervous system (PNS) to the central nervous system (CNS). In this study, we describe the organization of nodes of Ranvier at the trigeminal sensory and dorsal root entry zones of the rat. Caspr immunoreactivity (IR) was used to identify the paranodal region of nodes of Ranvier, while L-MAG-IR was used to identify CNS oligodendrocytes. Immunofluorescence confocal microscopy revealed a dense aggregation of nodes precisely at the PNS to CNS transition with prominent node-depleted zones on either side, while L-MAG-IR was confined to ensheathing fibers on the central side of nodes located in this dense band and identified these as transitional nodes. Morphometric analysis of the PNS and CNS sides of the trigeminal and the PNS side of the dorsal root entry zones confirmed the presence of virtually node-free domains flanking the transitional zone. Further, the reappearance of nodes on the far side of the node-free zones strongly correlated with nodal diameter, with small nodes reappearing first. These findings suggest that the PNS/CNS transition may represent the initial site of myelination of the primary afferent axon within this area.
Henry
Michael A
MA
Department of Surgical Dentistry, University of Colorado Health Sciences Center, 4200 E. 9th Avenue, Denver, CO 80262, USA. michael.henry@uchsc.edu
Rzasa
Rachael S
RS
Beeler
Joshua J
JJ
Levinson
S Rock
SR
D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000032:analysis* / Q000502:physiology; D002449:Cell Aggregation / Q000502:physiology; D005260:Female; D005727:Ganglia, Spinal / Q000737:chemistry* / Q000502:physiology; D011901:Ranvier's Nodes / Q000737:chemistry* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012668:Trigeminal Ganglion / Q000737:chemistry* / Q000502:physiology
D015816:Cell Adhesion Molecules, Neuronal; C105177:Cntnap1 protein, rat