Lanuza E, Halpern M
Department of Anatomy and Cell Biology, Health Science Center at Brooklyn, N.Y., USA.
Brain Behav Evol. 1998;51(1):1-22. doi: 10.1159/000006525.
This study reinvestigates the efferent projections of the main and accessory olfactory bulbs and describes for the first time the centrifugal projections to the main and accessory olfactory bulbs in the snake Thamnophis sirtalis, using the intraaxonal transport of the anterograde and retrograde tracer biotinylated dextran amine and the retrograde tracer horseradish peroxidase. The olfactory projection consists of three tracts: the lateral olfactory tract, which projects bilaterally to the lateral cortex and the rostral amygdala, crossing the midline through the stria medullaris-habenular commissure system; the intermediate olfactory tract, which projects ipsilaterally to the olfactory tubercle and contributes to the contralateral projection; and the medial olfactory tract, which projects ipsilaterally to the dorsomedial retrobulbar formation. The vomeronasal projection is formed by a single tract, the accessory olfactory tract, that projects ipsilaterally to the nucleus of the accessory olfactory tract, the medial amygdala and the nucleus sphericus. The centrifugal projections to the main and accessory olfactory bulb are composed of two components: one that arises in areas that receive the olfactory or vomeronasal input (neurons in the olfactory tubercle, retrobulbar formation and lateral cortex project to the main olfactory bulb; and neurons in the nucleus of the accessory olfactory tract, the medial amygdala and the nucleus sphericus project to the accessory olfactory bulb), and another that arises in areas not directly implicated in processing the chemosensory information (the nucleus of the diagonal band of Broca and the dorsal cortex). These data allow the recognition of the general pattern of organization of the reptilian olfactory and vomeronasal systems.
本研究重新调查了主嗅球和副嗅球的传出投射，并首次描述了对蛇类锦蛇主嗅球和副嗅球的离心投射，采用顺行和逆行示踪剂生物素化葡聚糖胺的轴突内运输以及逆行示踪剂辣根过氧化物酶。嗅觉投射由三条束组成：外侧嗅束，双侧投射至外侧皮质和吻侧杏仁核，通过髓纹-缰连合系统交叉中线；中间嗅束，同侧投射至嗅结节并参与对侧投射；内侧嗅束，同侧投射至球后背内侧结构。犁鼻器投射由单一的副嗅束形成，同侧投射至副嗅束核、内侧杏仁核和球状核。对主嗅球和副嗅球的离心投射由两个部分组成：一部分起源于接受嗅觉或犁鼻器输入的区域（嗅结节、球后结构和外侧皮质中的神经元投射至主嗅球；副嗅束核、内侧杏仁核和球状核中的神经元投射至副嗅球），另一部分起源于与化学感觉信息处理无直接关联的区域（布洛卡斜带核和背侧皮质）。这些数据有助于识别爬行类嗅觉和犁鼻器系统的总体组织模式。
