Journal of the Korean Academy of Pediatric Dentistry 2001;28(2):219-227.
Published online May 31, 2001.
ULTRASTRUCTURAL ANALYSIS OF TOOTH PULP AFFERENTS TERMINALS IN THE MEDULLARY DORSAL HORN OF THE RAT
Yong Chul Bae1, Eun Hee Lee1, Min Ki Choy1, Su Hyung Hong1, Hyun Jung Kim2, Soon Hyeun Nam2, Young Jin Kim2
1Department of Oral Anatomy, College of Dentistry, Kyungpook National University, Taegu, Korea
2Department of Pediatric Dentistry, College of Dentistry, Kyungpook National University, Taegu, Korea 
치수유래 구심성 신경섬유의 삼차신경 감각핵군에서의 연접특성
배용철1, 이은희1, 최민기1, 홍수형1, 김현정2, 남순현2, 김영진2
1경북대학교 치과대학 구강해부학교실
2경북대학교 치과대학 소아치과학교실*
Abstract
Little is known about processing mechanism of pain sensation of the oral cavity at the 1st synapse of trigeminal sensory nuclei. Serial ultrathin sections of tooth pulp afferent terminals, identified by the transganglionic transport of 1% wheatgerm agglutinin conjugated horseradish peroxidase, were investigated with electron microscope. Quantitative ultrastructural analysis was performed on digitizing tablet connected to Macintoshi personal computer (software; NIH Image 1.60, NIH, Bethesda, MD). Labeled boutons could be classified into two types by the shapes of containing vesicles : S bouton, which contained mainly spherical vesicles (Dia. 45-55 nm) and few large dense cored vesicles (Dia, 80-120nm), and LDCV bouton, which contained spherical vesicles as well as large number of large dense cored vesicles. Most of the parameters on the ultrastructural characteristic and synaptic organization of labeled boutons were similar between S and LDCV boutons, except shapes of containing vesicles. Majority of the labeled boutons showed simple synaptic arrangement. The labeled boutons were frequency presynaptic to dendritic spine, and to a lesser extent, dendritic shaft. They rarely synapsed with soma and adjacent proximal dendrite. A small proportion of labeled boutons made synaptic contacts with presynaptic, pleomorphic vesicles containing endings and synaptic triad. Morphometric parameters of labeled boutons including volume and surface area, total apposed area, mitochondrial volume, active zone area, vesicle number and density showed wide variation and these were not significantly different between S and LDCV boutons. The present study revealed characteristic features on ultrastructure and synaptic connection of pulpal afferents which may involved in transmission of oral pain sensation.
Key Words: Tooth pulp afferents, Ultrastructure, Synaptic organization, Medullary dorsal horn


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