Some effects of the degeneration of the perivascular nerve plexus in Rana pipiens.

• Main Author: Joftes, David Lion
• Language: en_US
• Published: Boston University 2015
• Online Access: https://hdl.handle.net/2144/10538

Thesis (Ph.D.)--Boston University === The literature on degenerative studies of the unmyelinated perivascular nerve plexus combined with histological examination is quite sparse. Tuckett (1895-1896) found that upon section of the branches of the superior cervical ganglion in the ox and rabbit histological and physiological changes began within twenty-four hours. At forty-three hours the irritability and conductivity of the peripheral stump were lost and the Remak fibers were degenerating. He believed that the Remak fiber had a sheath with a nucleus and that the "core" was homogenous and not composed of many fibrillae. In 1906 Lapinsky investigated the effects of denervation in the hind paw of the dog. The immediate effect was an increase in blood flow and vasodilation following denervation. The smooth muscle coat on the large arteries separated into individual cells and their nuclei swelled up and disintegrated. He was not able to find smooth muscle cells on the smaller arteries. He described the denervated arteries as losing tonus and being more fragile than normal. A somewhat more extensive study of the rabbit ear and the frog mesentery was published by Eugling (1908). Fifteen to sixteen days after denervation he found spindle-shaped nuclei with processes near the blood vessels. He believed that these were part of the degenerated nerve plexus. Since the nerve plexus had degenerated, Eugling did not think that these nuclei were ganglion-like though he did believe that they were part of the nervous system. Langley studied the effects of cutting the frog sciatic nerve and the nervus descendens communis in 1909. He reported that degeneration began in fourteen days and that the nerves disappeared in forty-two days. He believed that the axis cylinder lost its function throughout its whole length at about the same time. The sympathetic ganglia supplying the hind limbs of the cat were extirpated by Woollard (1926). He found no evidence for any "neural mechanism which survived proximal denervation". He also described the large branching spindle-shaped cells which persist after the degeneration of the nerve network. He thought that these cells were simply entwined with the nerve plexus proper. In 1929 Busch published on the problem of the innervation of the blood vessels and found no real histological differences among the frog, the guinea pig, the rabbit and man. According to Busch blood vessels, the sympathetic nerves of which had degenerated, did not completely regain tone up to ninety days following denervation. He considered the perivascular plexus to be sympathetic in nature. It was not possible for him to demonstrate autonomic ganglion cells in the limbs, and he believed that they were found only in the viscera . He obtained local contractions only, when stimulating vessels the nerve plexus of which had degenerated. In the present investigation the transilluminated denervated retrolingual membranes of living frogs, Rana pipiens, were observed directly through the microscope and simultaneously photographed with a motion picture camera by means of a light-splitting prism. Denervation was accomplished by sectioning the glossopharyngeal and hypoglossal nerve trunks. The animals were maintained at room temperature and fed one gram of hog liver three times weekly. When the required period of time (zero to two hundred and sixty-three days) had elapsed the retrolingual membrane was exposed according to the method of Pratt and Reid (1930), as modified by Fulton and Lutz (1942). Physiological observations were then made using unipolar electrical stimulation with an especially developed micro-electrode (Fulton, 1941) and a micromanipulator. Adrenalin was administered by means of the microinjection apparatus of the Emerson micromanipulator. Dilutions of Parke-Davis adrenalin of 1:4xl06 to 1:1x103 were used. At the conclusion of the physiological testing the retrolingual membranes were prepared for histological study by a modified Ehrlich's method (Busch, 1929). [TRUNCATED]