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Structure of warm fiber terminals in the pit membrane of vipers

1970; Academic Press; Volume: 31; Issue: 5-6 Linguagem: Inglês

10.1016/s0022-5320(70)90165-6

1878-2345

Shin‐Ichi Terashima, Richard C. Goris, Yasuji Katsuki,

Cellular transport and secretion

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.