Morphological Analyses of the Glomerulus in the Main Olfactory Bulb.

主嗅球（MOB）的肾小球被认为是嗅觉信息处理的功能单位。我们以前的大鼠MOB的分析揭示了肾小球的房室组织和两种类型的肾小球周围（PG）细胞，1型（PG 1）和2型（PG 2）PG细胞。我们发现，嗅神经轴突终末与投射神经元（僧帽细胞和簇状细胞）和PG 1的树突状簇形成突触接触，但不与PG 2的树突状簇形成突触接触。在本项目中，我们将我们的研究扩展到小鼠（包括基因操作小鼠）和其他哺乳动物肾小球的精细结构组织。用激光共聚焦扫描显微镜和电子显微镜观察，发现小鼠PG细胞内化学物质的共定位关系与以往报道的大鼠PG细胞不同，进一步证实了蝙蝠、树鼩、刺猬、鼹鼠、麝鼩和马岛猴的MOB中存在两种类型的PG细胞。因此，这些结构特征被认为是MOB的共同和重要的组织原则。我们还展示了复杂的神经元相互作用，通过化学突触和缝隙连接在肾小球。

Glomeruli of the main olfactory bulb (MOB) are now considered to serve as functional units in the olfactory information processing. Our previous analyses of the rat MOB revealed the compartmental organization of glomeruli and two types of periglomerular (PG) cells, type 1 (PG1)and type 2 (PG2) PG cells. We found that olfactory nerve axon terminals made synaptic contacts with dendritic tufts of both projection neurons (mitral and tufted cells) and PG1, but not of PG2, cells in the rat MOB. In the present project we extended our investigation to the fine structural organization of the glomeruli of mice (including genetically manipulated mice) and other mammals. Using the confocal laser scanning microscope and electron microscope, we found that the colocalization relationship of chemical substances in mouse PG cells was different from that of the rat PG cells reported previously.Furthermore, we confirmed the compartmental organization of the glomeruli and the presence of two types of PG cells in the MOB of bats, tree shrews, hedgehogs, moles, musk shrews and tenrecs. These structural features are therefore considered to be common and important organizational principles of the MOBs. We also exhibited complex neuronal interactions via chemical synapses and gap junctions in the glomerulus.