Elsevier

Brain Research

Volume 288, Issues 1–2, 12 December 1983, Pages 307-314
Brain Research

The periaqueductal gray projections to the rat spinal trigeminal, raphe magnus, gigantocellular pars alpha and paragigantocellular nuclei arise from separate neurons

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Possible collateral branches of periaqueductal gray axons which distribute to the nucleus raphe magnus, nucleus reticularis paragigantocellularis, nucleus reticularis gigantocellularis pars alpha and the spinal trigeminal nucleus were analyzed with the double fluorescent retrograde tracer technique. With the exception of a small number of double-labeled neurons observed in the periaqueductal gray following injections of fluorescent dyes into the nuclei reticularis paragigantocellularis and gigantocellularis pars alpha, no double-labeled cells were found in this midbrain region following injections of tracers into various combinations of the above 4 nuclear groups. The results of this investigation indicate that these 4 brainstem nuclei are innervated predominantly by separate neuronal populations within the periaqueductal gray.

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    This work was supported by Research Grants BSN 8214873 from the National Science Foundation and DE06682 from the National Institute of Dental Research.

    *

    The authors wish to thank Dr. George Leichnetz for providing us with a detailed protocol of the fluorescence technique used in this study and Drs. Alice Larson and Martin Wessendorf for their helpful comments during the preparation of this manuscript.

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