| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2003: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2002: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2001: ¥2,200,000 (Direct Cost: ¥2,200,000)
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| Research Abstract |
The infrared receptors (pit organs) of pit vipers and pythons have a dense capillary bed, in which blood flow increases markedly under infrared stimulation. It was surmised that parasympathetic elements of the facial nerve were involved in the control of this blood flow. However, resection of the peripheral nerve branches sending preganglionic fibers to the pits did not abolish this blood flow response, so it was presumed that the facial nerve was not directly involved. On the other hand, since little work has been done on the facial nerve of snakes, he afferent and efferent connections of the peripheral branches of he facial nerve were investigated in pit vipers by HRP and ChAT labeling. The morphology of the palatine nerve was similar to that of mammals, but there was remarkable difference in that of the chorda tympani. The chorda tympani did not form a lingual nerve, but the afferent fibers contained in it were all general somatic afferents. In addition to general visceral efferents
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, there were also special visceral efferents, and the peripheral mandibular branch of the facial nerve left the chorda tympani not inside, but outside the cranial bone. Since the capillary bed of the pits is a two-dimensional structure, the course of blood flow from arterioles through capillaries and out through venules is easily visualized. To study the blood flow, FITC dextran was injected to make the plasma fluoresce, and fluorescent microspheres were also introduced at the same time so that changes in blood flow with infrared stimulation could be visualized and measured. Under these conditions, blood flow in the pit was recorded, before, during, and after stimulation, on high-speed video at 250 frames/sec and analyzed with proprietary software. During stimulation, blood flow in the capillaries in the area of stimulation increased markedly at a statistical significance of P = 0.0007 in relation to the periods before and after stimulation. This phenomenon was not seen in either arterioles or venules, and suggests local control of capillary blood flow in the manner of an axonal reflex. Less
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