Laboratorio de Neuroplasticidad y Neurodegeneración, Departamento de Ciencias Médicas, Centro Regional de Investigaciones Biomédicas, Facultad de Medicina de Ciudad Real, Universidad de Castilla-la Mancha Ciudad Real, Spain.
Front Neuroanat. 2011 Jan 26;5:3. doi: 10.3389/fnana.2011.00003. eCollection 2011.
Most tetrapods possess two nasal organs for detecting chemicals in their environment, which are the sensory detectors of the olfactory and vomeronasal systems. The seventies' view that the olfactory system was only devoted to sense volatiles, whereas the vomeronasal system was exclusively specialized for pheromone detection was challenged by accumulating data showing deep anatomical and functional interrelationships between both systems. In addition, the assumption that the vomeronasal system appeared as an adaptation to terrestrial life is being questioned as well. The aim of the present work is to use a comparative strategy to gain insight in our understanding of the evolution of chemical "cortex." We have analyzed the organization of the olfactory and vomeronasal cortices of reptiles, marsupials, and placental mammals and we have compared our findings with data from other taxa in order to better understand the evolutionary history of the nasal sensory systems in vertebrates. The olfactory and vomeronsasal cortices have been re-investigated in garter snakes (Thamnophis sirtalis), short-tailed opossums (Monodelphis domestica), and rats (Rattus norvegicus) by tracing the efferents of the main and accessory olfactory bulbs using injections of neuroanatomical anterograde tracers (dextran-amines). In snakes, the medial olfactory tract is quite evident, whereas the main vomeronasal-recipient structure, the nucleus sphaericus is a folded cortical-like structure, located at the caudal edge of the amygdala. In marsupials, which are acallosal mammals, the rhinal fissure is relatively dorsal and the olfactory and vomeronasal cortices relatively expanded. Placental mammals, like marsupials, show partially overlapping olfactory and vomeronasal projections in the rostral basal telencephalon. These data raise the interesting question of how the telencephalon has been re-organized in different groups according to the biological relevance of chemical senses.
大多数四足动物都有两个用于探测环境中化学物质的鼻腔器官，这是嗅觉和犁鼻器系统的感觉探测器。70 年代的观点认为，嗅觉系统仅用于感知挥发性物质，而犁鼻器系统则专门用于检测信息素，但积累的数据表明，这两个系统在解剖和功能上存在着深层次的相互关系，这一观点受到了挑战。此外，犁鼻器系统作为适应陆地生活的假设也受到了质疑。本研究旨在采用比较策略，深入了解化学“皮质”进化的相关机制。我们分析了爬行动物、有袋类和胎盘哺乳动物的嗅觉和犁鼻器皮质组织，并与其他分类群的数据进行了比较，以便更好地理解脊椎动物鼻腔感觉系统的进化历史。我们通过向主要和辅助嗅球注射神经解剖学顺行示踪剂（葡聚糖胺），重新研究了王蛇（Thamnophis sirtalis）、短尾负鼠（Monodelphis domestica）和大鼠（Rattus norvegicus）的嗅觉和犁鼻器皮质。在蛇类中，内侧嗅觉束非常明显，而主要的犁鼻器接受结构——球状体核是一种折叠的皮质样结构，位于杏仁核的尾侧边缘。在无叉形大脑的有袋类动物中，嗅裂相对位于背侧，嗅觉和犁鼻器皮质相对扩张。胎盘哺乳动物和有袋类动物一样，在前脑基底部表现出部分重叠的嗅觉和犁鼻器投射。这些数据提出了一个有趣的问题，即根据化学感觉的生物学相关性，大脑皮质在不同的群体中是如何重新组织的。
