Richard C. Goris

Structure of warm fiber terminals in the pit membrane of vipers

The free nerve endings in the infrared receptor organ (the so-called “pit organ”) of an oriental pit viper, Trimeresurus f. flavoviridis, were studied with the electron microscope. The free nerve endings in this organ form a conglomeration of nonmyelinated nerve branchlets surrounding a few Schwann cells. We regard this conglomeration as a receptive unit, and have termed it the “terminal nerve mass”. Terminal nerve masses are about 40 μ in diameter and 10 μ thick; they are found in a single layer throughout the innervated membrane suspended in the pit cavity. The nerve branchlets comprising the masses contain a high concentration of mitochondria. Thin processes of the Schwann cells partially cover the surface of the branchlets, leaving certain areas completely bare. The structural relation between the Schwann cells and the branchlets seems functional, i.e., to provide the necessary nutrition for the cells without obstructing the reception of radiated energy over all the surface of the nerve mass. There are no synapses in the masses, indicating the absence of receptor interaction at this level of the receptor system.

Crotaline Pit Organs Analyzed as Warm Receptors

Afferent impulses from single-fiber preparations of the trigeminal nerve in Agkistrodon blomhoffi brevicauduswere recorded during steady and dynamic temperature stimulation of the sensory membrane in the facial pit. The thermoreceptors of the pit showed high sensitivity to the rate of change in receptor temperature. Changing the heat capacity of the pit membrane (a drop of water in the pit in the case of the laser and halogen lamp, and a drop of water covered by a plastic film in the case of flowing water) changed the pattern of response. When the heat capacity of the pit membrane is increased, responses approach those obtained in other warm receptors. The spatial gradient theory of Williams, whereby a reversal of heat energy flow is supposed to produce a reverse of response, was shown to be inapplicable to the pit receptors. Reversal of heat energy flow in the pits produced neither off-silence nor depression of response, and therefore direction of heat flow is not an important component of the stimulus for these receptors.

Infrared reception in oriental Crotaline snakes

Abstract 1. 1. The function of the facial pits in oriental Crotalines of the genera Trimeresurus and Agkistrodon was examined by electro-physiological recording from the nerves of the pit membrane. Functional response to pure infrared stimuli was demonstrated, confirming the results obtained from New World Crotalines by earlier workers. 2. 2. Response was tonic in the case of “normal” stimuli and phasic in the case of “painful” stimuli. 3. 3. Golay detector functioning of the pit organ was excluded, and the pit membrane was shown to lack any special absorption powers in the infrared spectrum. Control experiments on the analogous nerves of Colubrid snakes produced negative results. 4. 4. The pits function equally well at any temperature in the range at which the snakes are active.

Infrared sensory neurons in the trigeminal ganglia of crotaline snakes: Transganglionic HRP transport

Trigeminal neurons were labeled by inserting HRP into holes cut in the pit receptor membranes of a crotaline snake, Agkistrodon blomhoffi brevicaudus. Neurons were labeled in the ophthalmic ganglion and the maxillary division of the maxillo-mandibular ganglion, and the HRP was further transported across the ganglia and through the lateral descending trigeminal tract (dlv) to label axon terminals exclusively in the dlv nucleus (DLV). In 6 successful preparations, 7.1-19.3% of totals of 5568-5986 cells in the maxillary division of the ganglion were labeled, but none at all were labeled in the mandibular division. Only a few or none at all were labeled in the ophthalmic ganglion. Cells in the two ganglia ranged in size from 10 to 55 micrometers, but large cells (greater than or equal to 40 micrometers) were scarce (4.9% of the total population). All HRP-labeled neurons fell in the median range of 20-39 micrometers. We concluded that these ganglion cells were infrared neurons, and were therefore the origin of the A delta fibers in the pit membrane. There were no HRP-labeled neurons above or below this range, in spite of the fact that smaller cells (less than or equal to 19 micrometers) made up 35.8% of the total population. In normal Nissl preparations we found both light- and dark-staining cells, but the size range of neither corresponded to the size range of infrared neurons.

509 Substance P and calcitonin gene-related peptide immunoreactivity in the pit membrane of the mamushi

Tetsuo Kadota, Masato Nakano, Yoshitoshi Atobe, Kengo Funakoshi, Fumiaki Amemiya, Richard C. Goris, Reiji Kishida The pit vipers, exemplified by the mamushi, Agkistrodon blomhoffi, have a membrane in the infrared organ containing the receptor terminals of warm fibers and a capillary network, both in a highly developed state. The distribution of nerve fibers containing substance P and calcitonin gene-related peptide immunoreactivity was studied in the pit membrane. These nerve fibers were distributed throughout the pit membrane, but the receptor terminals were completely free of immunoreactivity. The pit membrane is innervated by the ophthalamic and maxillary branches of the trigiminal nerve. Fibers containing substance P entered the caudorostral part of the pit membrane through the course of the ophthalamic branch, the rostrodorsal part through the course of the deep branch of the maxillary, and the ventral part through the course of the superficial branch of the maxillary. Fibers containing calcitonin gene-related peptide showed a similar course and distribution.

Distribution patterns of postganglionic parasympathetic fibers in the infrared sensory organs of the mamushi, Agkistrodon blomhoffii

Pregangliomc neumns in Ranu wtcsbetanu are 01’ 111 o t) PC\: B cells and C cell\. in the +nul cord. larpc B cells arc I(~~tcd rostra1 to the smaller C cells. m-c\ ~oual). UT rcprtcd that m Ncnopus lae\-~< ~I-C~LII~, 7cylionic neurons XC dt\ iJcd mcd~olatc~ail~ into one group of large cell\ and another of smaller cells. In the prcscnt 11 OI-k. I\ c used HRP to ktudq the d~ytr~ buuon 2nd morpholog! of preganglionic neuronns that project 10 pm: crtcbrd s!mpathck ganglia 1.X wd X 01‘ Rufo ~apo!llcu\ formosus. HRP application prduced ~ps~latcral, n~cd~~~I;~k~d lakhng in L\\ o pl-cynglionlc group5 bet\\ een spinal scgmcnr\ V and VIII. Large neurons prcdommated in the medial group. and smaller newon PI-c&mma~cJ in the lute]-al gl-oup. Although this condition in Buli) rescmblcs that m Menopus, the large cell p~oups arc dlllcrcnt in thal thq arc locali/,cd In the more rostra1 spinal segments. We need to clari1.q the relation bet\reen the mediolutcral cell group’ and the preganglionic B and C cells.

Static response of infrared neurons of crotaline snakes—normal distribution of interspike intervals

Summary1.Background discharges (static responses) of warm fibers in the pit organs (infrared receptive organs) of two species of crotaline snakes were recorded at various temperatures (water, 18–33°C; air, 19–28°C). Mean interspike intervals

NADPH-diaphorase activity in the gastrointestinal canal of the mamushi

\left( {\bar X} \right)