Infrared sensory neurons in the trigeminal ganglia of the python (Python reticulatus)--a horseradish peroxidase study.

The infrared neurons innervating the 5 maxillary, 6 mandibular and 4 mental pit organs of the python, Python reticulatus, have been identified by means of retrograde transport of horseradish peroxidase. The neurons innervating the first maxillary pit are located in the ophthalmic ganglion; those innervating the second maxillary pit are in both the ophthalmic and maxillary ganglia; the neurons innervating the rest of the maxillary pits are located in the maxillary part of the ganglia. Neurons innervating the mandibular and mental pits are all located in the mandibular part of the ganglia. None of the pits are bilaterally innervated by the trigeminal nerve.