Matsui T, Tanaka K, Kobayashi Y
Department of Anatomy and Neurobiology, National Defense Medical College, Tokorozawa, Saitama, Japan.
Anat Histol Embryol. 2018 Feb;47(1):28-37. doi: 10.1111/ahe.12320. Epub 2017 Oct 19.
Histochemical organization of the Caudata olfactory system remains largely unknown, despite this amphibian order showing phylogenetic diversity in the development of the vomeronasal organ and its primary centre, the accessory olfactory bulb. Here, we investigated the glycoconjugate distribution in the olfactory bulb of a semi-aquatic salamander, the Japanese sword-tailed newt (Cynops ensicauda), by histochemical analysis of the lectins that were present. Eleven lectins showed a specific binding to the olfactory and vomeronasal nerves as well as to the olfactory glomeruli. Among them, succinylated wheat germ agglutinin (s-WGA), soya bean agglutinin (SBA), Bandeiraea simplicifolia lectin-I (BSL-I) and peanut agglutinin showed significantly different bindings to glomeruli between the main and accessory olfactory bulbs. We also found that s-WGA, SBA, BSL-I and Pisum sativum agglutinin preferentially bound to a rostral cluster of glomeruli in the main olfactory bulb. This finding suggests the presence of a functional subset of primary projections to the main olfactory system. Our results therefore demonstrated a region-specific glycoconjugate expression in the olfactory bulb of C. ensicauda, which would be related to a functional segregation of the olfactory system.
尽管有尾目在犁鼻器及其主要中枢副嗅球的发育中表现出系统发育多样性，但该目动物嗅觉系统的组织化学结构仍大多未知。在此，我们通过对所使用的凝集素进行组织化学分析，研究了半水生蝾螈日本剑尾螈（Cynops ensicauda）嗅球中的糖缀合物分布。11种凝集素显示出与嗅觉神经、犁鼻神经以及嗅觉小球有特异性结合。其中，琥珀酰化麦胚凝集素（s-WGA）、大豆凝集素（SBA）、单叶蔓荆凝集素-I（BSL-I）和花生凝集素在主嗅球和副嗅球的小球上表现出显著不同的结合情况。我们还发现，s-WGA、SBA、BSL-I和豌豆凝集素优先结合于主嗅球中前部的小球簇。这一发现表明主嗅觉系统存在初级投射的功能亚群。因此，我们的结果证明了日本剑尾螈嗅球中存在区域特异性糖缀合物表达，这可能与嗅觉系统的功能分离有关。
