Analysis of developmental mechanisms behind the evolution of diaphragm

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K06751
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 48010:Anatomy-related
• Research Institution: Niigata University
• Principal Investigator: Nagashima Hiroshi 新潟大学, 医歯学系, 准教授 (40435665)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 脊髄神経 / 発生

Outline of Final Research Achievements

Diaphragm is an evolutionary novelty in mammalian lineage. To unveil the developmental mechanisms underlying its evolution, we try to produce the diaphragm in chicken embryo. Development of the muscle structure is known to be very similar to that of limb muscles, and muscle evolution is assumed to be relatively easy because myoblasts from the cervical somites invade into extra limbs produced in the middle cervical portion. While the evolution of nerves innervating the diaphragm is assumed to be very hard since nerves did not invade the extra limb. We found middle cervical somites inhibited nerves extending into the extra limb. The somites only affected nerves rostral to the brachial plexus. The morphological meaning of the effect is still unknown, and it is possible that the effect is specific to avians, so investigation using other amniote species, such as turtles, would be needed.

Free Research Field

進化発生学

Academic Significance and Societal Importance of the Research Achievements

ニワトリの中頸部体節には他のレベルにはない軸索伸長阻害作用があるのが分かった。他の羊膜類の頸神経との比較から、この作用は鳥類特異的であり、鳥類進化の過程で獲得されたものと推測されるが、未だその形態的意味は不明である。また、この阻害作用に対しては運動ニューロンと感覚ニューロンで効果が異なっており、これらのニューロンの軸索伸長メカニズムの相違を明らかにするのに役立つものと考えられる。