Morphological Analyses of the Glomerulus in the Main Olfactory Bulb.

主要嗅球（MOB）的肾小球现在被认为是嗅觉信息处理的功能单位。我们之前对大鼠MOB的分析揭示了肾小球的室状组织和两种类型的肾小球周围（PG）细胞，1型（PG1）和2型（PG2） PG细胞。我们发现嗅觉神经轴突终末与大鼠MOB中投射神经元（二尖瓣细胞和簇状细胞）和PG1细胞的树突状簇形成突触接触，而不与PG2细胞形成突触接触。在本项目中，我们将研究扩展到小鼠（包括转基因小鼠）和其他哺乳动物肾小球的精细结构组织。利用激光共聚焦扫描显微镜和电子显微镜，我们发现化学物质在小鼠PG细胞中的共定位关系与之前报道的大鼠PG细胞的共定位关系不同。此外，我们在蝙蝠、树鼩、刺猬、鼹鼠、麝鼠和鼹鼠的MOB中证实了肾小球的区室组织和两种PG细胞的存在。因此，这些结构特征被认为是mob的共同和重要的组织原则。我们还通过肾小球中的化学突触和间隙连接展示了复杂的神经元相互作用。

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.