人類味覺系統的剖析 Anatomy ofhumantaste System Kuo Shyan LU, PhD 盧國賢 Department of Anatomy and Cell Biology College of Medicine NationalTaiwan University 台大醫學院解剖學暨細胞生物學科 I. Morphology of the taste bud (in human / rodents) 味蕾的形態學 II. Neurotransmitters and innervation of the taste bud 味蕾的神經支配與神經傳遞物質 III. Apoptosis of the taste bud cells 味蕾細胞的凋亡
Taste disorders Ageusia: 無味覺 complete loss of taste; Hypogeusia: 味覺遲鈍 diminished taste sensitivity; Hypergeusia: 味覺過敏 enhanced taste sensitivity; Dysgeusia: 味覺不良 distortionin in taste perception; (Seiden, 1997). 2010/5/11 Normal tougue surface transient lingual papillitis (TLP) an inflammation i of the round, mushroom shaped structures that house taste buds calledfungiform papillae ( 蕈狀舌乳突 )
廓狀舌乳突 葉狀舌乳突 絲狀舌乳突 蕈狀舌乳突 葉狀舌乳突 絲狀舌乳突 蕈狀舌乳突 支持細胞味覺細胞味孔 輪廓狀舌乳突 味蕾
http://embryology.med.unsw.edu.au/notes/images/senses/nature05401 f1.2.jpg I. Morphology of the taste bud (in human/rodents) 味蕾的形態學
Filiform papilla Vallate papilla Foliate papilla Fungiform papilla Vallate papilla CT core trench Taste bud Von Ebner s gland
Average taste pore number per papilla: 85.6 ± 1.67 (N=4) Distribution density of taste pore:1.89 ± 0.5 per 1000 μm 2 (N=8)
Average size of a mouse taste bud: a = 65 μm b= 45 μm a b
Isolated taste cells T. E. Finger : Chem. Senses 30 (suppl 1): i54 i55, 2005
結論 ( 一 ) 味覺感受器細胞 (taste t receptor cells) 位於味蕾 (taste t buds) 內, 而味蕾則位於舌頭 腭 (palate) 咽(pharynx) 和會厭 (Epiglottis) 之上皮內 A. 在人類, 有大約 2000-5000 味蕾, 每一個味蕾包含 50-150 個味覺感受器細胞 B. 多數味蕾位在舌頭背部表面的舌乳突上 C. 不同於多數神經元細胞, 味覺感受器細胞會再生 ; 其壽命是大約 2 星期 D. 每個味覺感受器細胞可對 4-5 個基本刺激反應, 且可產生不同的組合反應 II. Neurotransmitters and innervation of the taste bud 味蕾的神經支配與神經傳遞物質
丘腦腹後內側核 初級味覺皮質區 側下視丘 杏仁核 第七對 ( 顏面 ) 鼓索神經 腦神經 孤立束核第九對 ( 舌咽 ) 腦神經 延髓尾部第十對 ( 迷走 ) 腦神經
Subgemmal nerve fibers Intragemmal nerve fibers Perigemmal nerve fibers Taste cells PGP9.5 ++ ++ ++ ++ 5HT ++ + + + SP + + + ± NOS + - - + BDNF + - - ++ NGF + - - ++ ++ Number of "+ sign indicates the relative staining intensity of the immunoreactivity, and " sign indicates no immunoreactivity. PGP 9.5 Protein Gene Product 9.5, CGRP Calcitonin Gene Related Peptide, SP Sbstance P, NOS Nitric Oxide Synthase, BDNF Brain derived Neurotrophic Factor, NGF Nerve Growth Factor
結論 ( 二 ) 1. 輪廓乳頭具有許多的味蕾, 且味蕾具有不同型式的細胞, 某些細胞具有神經元的特性 味蕾的神經傳物質是 5-HT 或 substance P 2. 味覺信息經味覺感受器細胞, 並通過第七 九 十 (CN VII, IX & X) 投射至腦幹 (brainstem) 之孤立束核 (nucleus tractus solitarius), 然後再投射至丘腦 杏仁核 或丘腦腹後內側核, 然後再投射至大腦皮質 (erebral cortex insular cortex) III. Apoptosis and development of the taste bud cells 味蕾細胞的發育與凋亡
control 1d 5d 3w 9w 24w
3 days after glossopharyngeal neurectomy 7 days after glossopharyngeal neurectomy
結論 ( 三 ) 味蕾是一種 dynamic structure, 在正常情況下, 也有稀少的細胞凋亡 (apoptosis) 的現象 支配味蕾的神經被切除後, 短期內, 細胞凋亡有增加的現象 但長時期切除神經則味蕾會消失 神經支配是維持味蕾正常功能所必需的 味蕾發育過程中,PGP9.5 的出現較早於 NGF 或 BDNF 的出現, 故推論 : 輪廓乳頭的形成不需神經存在, 然而味蕾的分化則需神經支持 神經滋養因子有誘導神神經到新生的輪廓乳頭及味蕾的作用
Contributors of this presentation: Ms. Ming Huei Chen ( 陳敏惠 ) Dr. Chung Liang Chien ( 錢宗良 ) Dr. Hsiu Chou Chou ( 周繡珠 ) Dr. Yi Jen Huang ( 黃怡仁 ) Dr. Ko Kaung Liao ( 廖克剛 ) 謝謝! Department of Anatomy and Cell Biology College of Medicine National Taiwan University This work was supported in part by grants from National Science Council.