| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1994: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Research Abstract |
Developmental changing of fuction and distribution of taste buds on the soft palate and fungiform papilla were investigated in the rat. Taste buds on the soft palate produced robust gustatory responses to sugars, especially for sucrose, and various D-amino acids. They showed little sensitivity for amiloride which markedly inhibit taste responses to Na salts. On the contrary, taste buds on the fungiform papilla indicated low taste sensitivities for sugars and amino acids, while remarkable inhibition by amiloride for Na salts A was observed. The number of taste buds of the fungiform papillae was approximately 100, and reached 200 at three weeks of age. However, maturated taste buds were only 15% of all and reached 90% at two weeks of age. On the other hand, 180 taste buds were distributed on the soft palate and 80% of those were maturated at birth and reached 90% at two weeks of age. The number of taste buds on circumvallate papillae was only 40 at birth and reached 400 at four weeks of age. No taste bud was observed on the foliate papillae at birth and observed 300 at three weeks of age. Although the numbers of taste buds were different among species, similar difference of maturation of taste buds between the soft palate and the tongue was observed in the mouse and gerbil. In the marmoset, the number of the taste buds of fungiform papillae was approximately three times larger than that on the soft palate at tree days of age, while maturated buds were 80% in the soft palate and 60% in the fungiform papillae. Although the number of taste buds apparently decreased at two months of age and reached one third at nine months, while the decreasing of buds in the fungiform papillae was slight. These results indicated that the function of the taste buds on the soft palate was quite different from those in the tongue, playing important role on neonatal stage in mammals.
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