Huang Y J, Lu K S
Department of Anatomy, College of Medicine, National Taiwan University, Taipei, Republic of China.
J Anat. 1996 Oct;189 ( Pt 2)(Pt 2):315-24.
The innervation pattern by primary afferent nerve fibres and the neurotrophic effect on taste cells were investigated in the guinea pig vallate taste bud by means of glossopharyngeal neurectomy and horseradish peroxidase (HRP) or wheat germ agglutinin-horseradish peroxidase (WGA-HRP) tracing. In the glossopharyngeal neurectomy study, taste buds in the vallate papillae of adult guinea pigs were denervated by unilateral resection of the right glossopharyngeal nerve. Denervated animals were killed on days 1, 3 and 5 and weeks 1-9, 12 and 24 postneurectomy. The results showed that, on the denervated side, the taste buds decreased significantly in number during the 1st 2 wk, and disappeared completely by wk 3; no mature taste buds were present even 24 wk after neurectomy. This suggests that the vallate taste buds disappear in the absence of the glossopharyngeal nerve. In the neural tracing study, HRP or WGA-HRP was injected into the proximal end of the right glossopharyngeal nerve, near the jugular foramen. After a survival time of 24 h, the vallate papillae were sectioned and examined by light and electron microscopy. Light microscopy revealed that the HRP or WGA-HRP-labelled fibres innervated the vallate taste buds of the injected side. Most of the taste cells in the buds were labelled with HRP or WGA-HRP reaction products from the basal to the apical region. At the ultrastructural level, the reaction products were confined to the cytoplasm of the labelled cells, which were identified as type I, II and III cells, but not basal cells. Labelled intragemmal nerve profiles were seen among the taste cells. No synapse formation was seen with nerve profiles abutting on type I and II cells, whereas on certain type III cells, typical synapses were formed. We conclude that both the right and left vallate papilla in the guinea pig are unilaterally innervated by the glossopharyngeal nerve without cross-innervation.
通过舌咽神经切除术以及辣根过氧化物酶（HRP）或麦胚凝集素 - 辣根过氧化物酶（WGA - HRP）追踪技术，研究豚鼠轮廓乳头味蕾的初级传入神经纤维支配模式及其对味细胞的神经营养作用。在舌咽神经切除术研究中，成年豚鼠轮廓乳头中的味蕾通过单侧切除右侧舌咽神经而失神经支配。失神经支配的动物在神经切除术后第1、3和5天以及第1 - 9、12和24周处死。结果显示，在失神经支配侧，味蕾数量在最初2周内显著减少，到第3周时完全消失；即使在神经切除术后24周也未出现成熟的味蕾。这表明在没有舌咽神经的情况下轮廓乳头味蕾会消失。在神经追踪研究中，将HRP或WGA - HRP注入右侧舌咽神经靠近颈静脉孔的近端。存活24小时后，将轮廓乳头切片并进行光镜和电镜检查。光镜显示，HRP或WGA - HRP标记的纤维支配注射侧的轮廓乳头味蕾。味蕾中的大多数味细胞从基部到顶部区域都被HRP或WGA - HRP反应产物标记。在超微结构水平上，反应产物局限于标记细胞的细胞质中，这些细胞被鉴定为I型、II型和III型细胞，但不包括基底细胞。在味细胞之间可见标记的味蕾内神经轮廓。未观察到与I型和II型细胞相邻的神经轮廓形成突触，而在某些III型细胞上形成了典型的突触。我们得出结论，豚鼠的左右轮廓乳头均由舌咽神经单侧支配，不存在交叉支配。
