Aicardi Stefano, Amaroli Andrea, Gallus Lorenzo, Di Blasi Davide, Ghigliotti Laura, Betti Federico, Vacchi Marino, Ferrando Sara
Department of Earth, Environmental, and Life Sciences (DISTAV), University of Genoa, Corso Europa, 26, 16132, Genoa, Italy.
Department of Surgical Sciences and Integrated Diagnostics (DISC), University of Genoa, Largo Rosanna Benzi, 8, 16132, Genoa, Italy; Department of Orthopedic Dentistry, Institute of Dentistry, I. M. Sechenov First Moscow State Medical University, Bol'shaya Pirogovskaya Ulitsa, 19с1, Moscow, 119146, Russia.
Zoology (Jena). 2020 Aug;141:125796. doi: 10.1016/j.zool.2020.125796. Epub 2020 Apr 26.
In vertebrates, the olfactory bulb (OB) is the zone of the brain devoted to receiving the olfactory stimuli. The size of the OB relative to the size of the brain has been positively correlated to a good olfactory capability but, recently, this correlation was questioned after new investigation techniques were developed. Among them, the isotropic fractionator allows to estimate the number of neurons and non-neurons in a given portion of nervous tissue. To date, this technique has been applied in a number of species; in particular the OB was separately analyzed in numerous mammals and in a single crocodile species. Thus, a quantitative description of the OB's cells is available for a small portion of vertebrates. Main aim of this work was to apply isotropic fractionator to investigate the olfactory capability of elasmobranch fishes, whose traditional concept of outstanding olfaction has recently been scaled down by anatomical and physiological studies. For this purpose, the OB of two elasmobranch species, Galeus melastomus and Scyliorhinus canicula, was studied leading to the determination of the number of neurons vs non-neurons in the OB of the specimens. In addition, the obtained cell quantification was related to the olfactory epithelium surface area to obtain a new parameter that encapsulates both information on the peripheral olfactory organ and the OB. The analyzed species resulted in an overall similar quantitative organization of the peripheral olfactory system; slight differences were detected possibly reflecting different environment preference and feeding strategy. Moreover, the non-neurons/neurons ratio of these species, compared to those available in the literature, seems to place elasmobranch fishes among the vertebrate species in which olfaction plays an important role.
在脊椎动物中，嗅球（OB）是大脑中专门用于接收嗅觉刺激的区域。嗅球大小与大脑大小的比例与良好的嗅觉能力呈正相关，但最近，在新的研究技术出现后，这种相关性受到了质疑。其中，等密度分离法可以估计给定神经组织部分中神经元和非神经元的数量。迄今为止，这项技术已应用于许多物种；特别是在众多哺乳动物和单一鳄鱼物种中对嗅球进行了单独分析。因此，对于一小部分脊椎动物，已有关于嗅球细胞的定量描述。这项工作的主要目的是应用等密度分离法来研究板鳃鱼类的嗅觉能力，其传统的卓越嗅觉概念最近已被解剖学和生理学研究下调。为此，对两种板鳃鱼类，即黑点猫鲨（Galeus melastomus）和斑纹鲨（Scyliorhinus canicula）的嗅球进行了研究，从而确定了标本嗅球中神经元与非神经元的数量。此外，将获得的细胞定量与嗅觉上皮表面积相关联，以获得一个新参数，该参数包含了关于外周嗅觉器官和嗅球的信息。分析的物种在外周嗅觉系统的整体定量组织上总体相似；检测到的细微差异可能反映了不同的环境偏好和摄食策略。此外，与文献中可用的物种相比，这些物种的非神经元/神经元比率似乎使板鳃鱼类处于嗅觉起重要作用的脊椎动物物种之中。
