Ultrastructure and synaptology of the paratrigeminal nucleus in the rat: Primary pharyngeal and laryngeal afferent projections

Dale Saxon, David A. Hopkins

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

The paratrigeminal nucleus (PTN) receives primary afferent projections from the aerodigestive tract and orofacial regions and plays a role in the integration of visceral and somatic information. This study describes the fine structure of the rat PTN and the synaptology of primary afferent projections from the pharynx and larynx. Injections of wheat germ agglutinin-horseradish peroxidase (WGA-HRP) or cholera toxin-HRP (CT-HRP) were made into the wall of the pharynx or larynx to label primary afferent axon terminals. Light microscopic observations demonstrated that afferent axons terminated bilaterally in overlapping fields in the PTN. Electron microscopic observations of the PTN revealed that there were three distinct classes of neurons, based on morphology and axosomatic contacts. The most abundant neurons, Type 1, were fusiform in shape and received very few or no axosomatic contacts. Type 2 neurons contained prominent Nissl substance (rough endoplasmic reticulum) and few axosomatic contacts, while Type 3 neurons had many axosomatic synapses. Terminals containing round, clear vesicles and forming asymmetric contacts (round asymmetric, RA) with dendrites were the predominant synaptic type in the PTN. Primary afferent terminals from the pharynx and larynx were of the RA type and formed synaptic contacts with small-diameter (<1 μm) dendrites. Visceral primary afferent inputs from the pharynx and larynx overlap with trigeminal somatic afferents in the PTN and have similar synaptic morphology. The results support the concept that the PTN provides an anatomical substrate for mediating viscerovisceral and somatovisceral reflexes via efferent connections with autonomic centers in the brainstem.

Original languageEnglish
Pages (from-to)220-234
Number of pages15
JournalSynapse
Volume59
Issue number4
DOIs
StatePublished - Mar 15 2006

Fingerprint

Larynx
Pharynx
Neurons
Dendrites
Visceral Afferents
Wheat Germ Agglutinins
Rough Endoplasmic Reticulum
Presynaptic Terminals
Synapses
Brain Stem
Axons
Reflex
Electrons
Light
Injections

Keywords

  • Aerodigestive tract
  • Lamina I/II
  • Medullary dorsal horn
  • Orofacial
  • Transganglionic

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology
  • Pharmacology
  • Advanced and Specialized Nursing

Cite this

Ultrastructure and synaptology of the paratrigeminal nucleus in the rat : Primary pharyngeal and laryngeal afferent projections. / Saxon, Dale; Hopkins, David A.

In: Synapse, Vol. 59, No. 4, 15.03.2006, p. 220-234.

Research output: Contribution to journalArticle

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