Three times as many lamina I neurons project to the periaqueductal gray than to the thalamus: a retrograde tracing study in the cat.
The number and distribution of lamina I neurons projecting to the periaqueductal gray (PAG) were examined by a retrograde tracing study in the cat. WGA-HRP injections in the intermediate and caudal PAG resulted in as much as 1600 labeled lamina I neurons throughout the length of the spinal cord, counted in a 1:4 series of sections. The lamina I-PAG projection was predominantly contralateral and most labeled lamina I neurons were found in the enlargements. Comparing these results with the number of lamina I-thalamic neurons leads to the conclusion that in the cat about three times as many lamina I neurons project to the PAG than to the thalamus. Considering this, one can conclude that the spino-PAG system is a virtually neglected area in pain research.
Mouton
L J
LJ
Department of Anatomy and Embryology, Faculty of Medical Sciences, Rijksuniversiteit Groningen, The Netherlands. l.j.mouton@med.rug.nl
Holstege
G
G
D000818:Animals; D002415:Cats; D015335:Molecular Probes; D009474:Neurons / Q000502:physiology*; D010487:Periaqueductal Gray / Q000502:physiology*; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology*; D013133:Spinothalamic Tracts / Q000166:cytology / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology*; D013788:Thalamus / Q000502:physiology*; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
D015335:Molecular Probes; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate