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KMID : 0376219750120020453
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Chonnam Medical Journal
1975 Volume.12 No. 2 p.453 ~ p.464
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Studies of the Autonomic Innervation of the Submaxillary Gland in the Cat-Responses of the Submaxillary Gland to Stimulation of the Chorda Tympani and the Cervical Sympathetics, and Electron Microscopic Observation of the Contractile Elements of the Subma
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Abstract
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The submaxillary gland is the principal salivary gland under the autonomic innervation. Numerous reports described that electrical stimulation of the chorda tympani provokes abundant salivary secretion in a few seconds, but stimulation of the cervical sympathetics produces only a scanty flow of saliva with considerable time delay and repetitive stimulations fail to elicit even a scanty salivary flow. Accordingly, it is well known that the chorda tympani contains salivary secretary fibers. It is, however, still uncertain whether the scanty salivary flow by the cervical sympathetics is actual secretion from the gland cells or expelled saliva which was already present in the submaxillary duct. The role of the sympathetic fibers to this gland is not clear. Since the myoepithelial cells as a contractile element are found in salivary gland, existence of such contractile element in the salivary duct has been also suggested.
It has been generally accepted that stimulus frequency for maximal response is different, depending on the nature of the nerve fiber, parasympathetic and sympathetic. Many workers attempted to find out the optimal frequency to elicit the maximal secretory responses in stimulating the chorda tympani, but their results were in considerable variance.
The present studies were designed to examine, in the anesthetized cats with acutely cannulated submaxillary duct, the effects of the stimulation of the chorda tympani and the cervical sympathetics, the responses of the submaxillary gland to some autonomic drugs and the optimal frequency to elicit the maximal secretory response. To explore the contractile elements of the submaxillary duct; cytological studies were also performed. The results obtained were as follows:
1. Spontaneous salivary secretion was not observed.
2. Stimulation of the chorda tympani immediately provoked abundant sal vary secretion, and responses of the submaxillary gland to the chorda tympani was completely abolished by pretreatment with atropine, a cholinergic bloing agent.
3. The most effective frequency of the square wave for the chorda tympani stimulation was 10 cycles per second.
4. Stimulation of the cervical sympathetics and the administration of orepinephrine produced a scanty salivary flow with considerable time delay and repetitive stimulation of this nerve failed to elicit even a scanty salivary flew. In some cases, the response of the gland to the cervical- sympathetic stir ulation was completely lacking.
5. Myoepithelial and smooth muscle cells were identified cytologically "in the submaxillary duct and these cells seem to function as the contractile meats.
6. These results described above indicate that the scanty salivary flow from the submaxillary gland by the cervical sympathetics is not actual secretion from the gland, but merely the elimination of saliva stagnated in the d ct due to contraction of the myoepithelial cells and smooth muscle fibers of the duct-wall.
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