| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1999: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1998: ¥1,500,000 (Direct Cost: ¥1,500,000)
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| Research Abstract |
In order to analyze how sensory nerve endings detect mechanical stimuli, the fine structure of the endings and their relationships with surrounding tissues were investigated by scanning electron microscopy after exposure of the objects with NaOH maceration, and by transmission electron microscopy according to conventional methods. Some specimens were also examined by immunohistochemistry for protein gene product-9.5 and for S-100 protein in order to identify axon terminals and Schwann cells, respectively. Observations were performed in rats, and reported on Ruffini endings, which have been known as slowly-adapting mechanoreceptors monitoring tension of periodontal ligaments, and lanceolate endings, which have been regarded as rapidly-adapting receptors detecting acceleration and deceleration of vibrissal movements. Both types of receptors consisted of two parts: principal portions displaying common features, and terminal appendices specific to the receptor types. The former portions we
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re represented by triplet units in each of which a flattened axon ending was flanked on each side by a Schwann cell lamella, as reported previously. These portions were isolated from surrounding tissues by thick basal lamina-like matrices. The latter, terminal appendices of the nerve endings were characterized by long projections of Schwann cells fanning out distally and by fine axon fingers associated with their bases. In the periodontal Ruffini endings, terminal processes of Schwann cells were tongue-like in shape, and tightly twined around ligament fibers. In the lanceolate endings associated with vibrissae, on the other hand, Schwann cell processes were cord-like, and extended straight in an amorphous matrix to terminate as flattened ends on rigid connective tissue elements. Previous observations in thin tissue sections failed to demonstrate these specialized structures confined to distal ends of the sensory corpuscles. The present study proposes these structures as possible receptor sites which would effectively transmit mechanical distortions or movements of surrounding tissues to the sensory devices. Less
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