Early migratory neurons from the olfactory placode are putative guidepost cells in the initial formation of the olfactory nerve tract

2019 Fiscal Year Final Research Report

• Project/Area Number: 16K08454
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: General anatomy (including histology/embryology)
• Research Institution: Juntendo University
• Principal Investigator: MURAKAMI Shizuko 順天堂大学, 医学(系)研究科(研究院), 非常勤助教 (20255649)
• Co-Investigator(Kenkyū-buntansha): 鈴木 ちぐれ 順天堂大学, 医学部, 助教 (40536629)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 嗅プラコード / 嗅神経 / 嗅覚回路 / ニューロン移動 / ガイドポスト細胞 / GnRHニューロン / ニワトリ胚

Outline of Final Research Achievements

The early developing olfactory placode (OP) generates the olfactory sensory neurons (OSN), as well as other neuronal cells, which migrate from the OP into the mesenchyme. In chick embryos, the early migrating cells from the OP which express polysialic acid, an immature neuron marker, form the cellular cord extending from the placode to the telencephalon at embryonic day (E) 3. The physical destruction of the cellular cord induced a lack of OSN axon innervation of the olfactory bulb and the entry of the GnRH neurons into the forebrain. DiI application or GFP electroporation into the OP at E2.5 revealed that the OP-derived early migratory cells accumulated in the region close to the olfactory nerve-olfactory bulb junction at E4.5-6. In contrast, the cells labeled at E3.5 did not form a cluster in this region. These results suggest that the OP-derived early migratory neurons may act as guidepost for the initial formation of the olfactory nerve tract.

Free Research Field

神経発生学

Academic Significance and Societal Importance of the Research Achievements

嗅神経伸長前に嗅プラコード上皮から細胞が終脳に向かって移動し、細胞塊を形成する現象は多くの動物で観察されているが、その役割は明らかでない。本研究によって、初期の嗅プラコード由来移動細胞は嗅神経路形成に必須の細胞構造を形成することが判明し、さらに嗅神経と終脳の結合を決めるガイドポストとして機能する可能性が示された。これらは、嗅覚発生における新規の知見であり、初期の嗅覚回路形成機構における新しい概念を提示している。