Barreiro-Iglesias Antón, Anadón Ramón, Rodicio María Celina
Department of Cell Biology and Ecology, CIBUS, Faculty of Biology, University of Santiago de Compostela, Santiago de Compostela, Spain.
Brain Behav Evol. 2010;75(4):241-50. doi: 10.1159/000315151. Epub 2010 Jul 24.
The present is a review of the gustatory system of lampreys, which are representative of the earliest vertebrates. They are the oldest extant vertebrates that possess taste buds. Because of the phylogenetic position of lampreys, the study of their gustatory system will provide important information to help understand the early evolution of this system in vertebrates. The taste buds of larval lampreys, which are papillae located on the first six pairs of gill arches facing the water current, respond to classical taste substances. They consist of two types of tall differentiated cells, serotonergic biciliated taste receptors ('light' cells) and microvillous sustentacular cells ('dark cells'). The taste buds also contain basal proliferative cells. Afferent gustatory fibers of the glossopharyngeal and vagal nerves innervate the taste buds of lampreys and contact the basal surface of the biciliated cells without entering the bud. Central processes of the glossopharyngeal and vagal cranial nerves terminate in a caudal rhombencephalic region that may correspond to the nucleus of the solitary tract of gnathostomes. To date, most studies in lampreys have focused on characterizing taste buds; future research should focus on the central processing of the gustatory information. Here we will review the current knowledge about the gustatory system of lampreys to provide a basis for establishing the direction of further studies of this chemosensory system.
本文是对七鳃鳗味觉系统的综述，七鳃鳗是最早的脊椎动物的代表。它们是现存最古老的拥有味蕾的脊椎动物。由于七鳃鳗的系统发育位置，对其味觉系统的研究将为理解脊椎动物中该系统的早期进化提供重要信息。幼体七鳃鳗的味蕾是位于面对水流的前六对鳃弓上的乳头，对经典味觉物质有反应。它们由两种高度分化的细胞组成，血清素能双纤毛味觉受体（“亮”细胞）和微绒毛支持细胞（“暗”细胞）。味蕾还含有基底增殖细胞。舌咽神经和迷走神经的传入味觉纤维支配七鳃鳗的味蕾，并接触双纤毛细胞的基底表面而不进入味蕾。舌咽神经和迷走脑神经的中枢突终止于尾侧菱脑区域，该区域可能对应于有颌类动物的孤束核。迄今为止，对七鳃鳗的大多数研究都集中在味蕾的特征描述上；未来的研究应集中在味觉信息的中枢处理上。在这里，我们将综述关于七鳃鳗味觉系统的现有知识，为确定对这个化学感觉系统进一步研究的方向提供基础。
