Hosley M A, Hughes S E, Oakley B
J Comp Neurol. 1987 Jun 8;260(2):224-32. doi: 10.1002/cne.902600206.
Bilateral innervation allows more than 80% of the 610 vallate taste buds to survive removal of one IXth nerve in adult rats. Removal of both IXth nerves in neonatal or adult rats results in the absence of taste buds. In studying development, we found that removing or crushing one IXth nerve in three-day-old neonates profoundly decreased the number of vallate taste buds that subsequently developed. Specifically, after removal of one IXth nerve at 3 days, only 228 taste buds formed, compared with 496 taste buds that one nerve would maintain in adults. Thus, during normal development, the right and left IXth nerves interact synergistically, as at least 150 more taste buds develop than predicted by the sum of the independent action of each IXth nerve. This suggests that vallate taste buds are induced by the IXth nerve. A second example of synergism, representing evidence for the neural induction of taste buds, came from experiments in which we crushed the left IXth nerve 3 days after birth and found that these regenerated IXth nerve axons induced 4 times as many taste buds in the presence of the normal right IXth nerve (118 taste buds) as in its early absence (30 taste buds). We conclude that taste buds are neurally induced and that axons of the IXth nerve interact synergistically in inducing them, rather than competing for targets. We propose that in development innervated progenitor cells form stem cells which lead to taste bud cells.
双侧神经支配使得成年大鼠中610个轮廓乳头味蕾中的80%以上在切除一侧第九对脑神经后得以存活。在新生大鼠或成年大鼠中双侧切除第九对脑神经会导致味蕾缺失。在研究发育过程中，我们发现，在出生三天的新生大鼠中切除或挤压一侧第九对脑神经会显著减少随后发育的轮廓乳头味蕾数量。具体而言，在出生3天时切除一侧第九对脑神经后，仅形成了228个味蕾，而在成年大鼠中一侧神经可维持496个味蕾。因此，在正常发育过程中，左右两侧第九对脑神经协同作用，因为发育出的味蕾比每侧第九对脑神经独立作用之和所预测的至少多150个。这表明轮廓乳头味蕾是由第九对脑神经诱导产生的。协同作用的第二个例子为味蕾神经诱导提供了证据，来自于我们在出生后3天挤压左侧第九对脑神经的实验，结果发现，在右侧第九对脑神经正常存在的情况下（118个味蕾），这些再生的第九对脑神经轴突诱导产生的味蕾数量是其早期缺失时（30个味蕾）的4倍。我们得出结论，味蕾是由神经诱导产生的，并且第九对脑神经的轴突在诱导味蕾时协同作用，而非竞争靶标。我们提出，在发育过程中，受神经支配的祖细胞形成干细胞，进而产生味蕾细胞。
