title: Morphology and synaptic connections of unmyelinated primary axons in the border zone of rat trigeminal nucleus oralis.
abstract: This anterograde horseradish peroxidase study examines the morphology and synaptic connections of a population of primary axons which terminate in the dorsal one-half of the border zone (BZ) of rat trigeminal nucleus oralis. Unmyelinated parent fibers in the spinal V tract enter BZ directly and each terminate by continuing as a sparsely branched, long caudally directed strand containing several axonal endings. Primary endings lie in glomeruli where each forms an asymmetrical synapse on a central dendrite. Other glomerular components include two types of non-primary endings. One contains flattened synaptic vesicles, and forms a symmetrical synapse on either the primary ending or the central dendrite, while the other contains pleomorphic synaptic vesicles and establishes a symmetrical synapse on the central dendrite.
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure; D003712:Dendrites / Q000648:ultrastructure; D008297:Male; D008854:Microscopy, Electron; D051381:Rats; D011919:Rats, Inbred Strains; D013569:Synapses / Q000648:ultrastructure; D013572:Synaptic Vesicles / Q000648:ultrastructure; D014278:Trigeminal Nuclei / Q000166:cytology* / Q000648:ultrastructure