Midbrain paralemniscal projections to the facial nucleus: an anatomical and immunohistochemical study.
Serial 30 microns-thick sections through the midbrain tegmentum were stained with cresyl violet. The PL was found to be situated along the medial edge of the lateral lemniscus. The PL consisted of small- (10-15 microns) and medium-sized neurons (25-35 microns), and was the most prominent at the caudal level of the superior colliculus. In order to confirm the existence of the inhibitory paralemniscal-facial pathway, a combined HRP and immunohistochemical technique was use in the rat. This experiment revealed that 10.9% of the total number of GABA immunoreactive PL neurons also labeled with HRP after HRP injection was made in the medial part of the facial nucleus (FN). Electron microscopic observations were carried out on the medial part of the facial nucleus (FN) after kainic acid injection was made into the contralateral PL in the cat. The majority of degenerating PL fibers were ranged from 0.5 to 3.1 microns in diameter and made synaptic contacts with somata, proximal dendrites and dendritic profiles. These fibers, containing either round or pleomorphic vesicles, formed asymmetrical or symmetrical synapses. It was of particular interest in the present study that 40.7% of the total number of degenerating fibers make synaptic contacts with large dendrites more than 3.0 microns in diameter.
Chen
X H
XH
Department of Anatomy, Kagawa Medical School, Japan.
Itoh
M
M
Miki
T
T
Ichiyama
M
M
Fujimoto
Y
Y
Sun
W
W
Takeuchi
Y
Y
D000818:Animals; D002415:Cats; D007150:Immunohistochemistry; D008854:Microscopy, Electron; D009046:Motor Neurons / Q000648:ultrastructure*; D009434:Neural Pathways / Q000648:ultrastructure; D051381:Rats; D013569:Synapses / Q000648:ultrastructure; D013681:Tegmentum Mesencephali / Q000648:ultrastructure*