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Development of the dorsal ramus of the spinal nerve in the mouse embryo: Involvement of semaphorin 3 A in dorsal muscle innervation
Author(s) -
Masuda Tomoyuki,
Taniguchi Masahiko,
Sakuma Chie,
Yamagishi Toshiyuki,
Ueda Shuichi,
Kawaguchi Masahumi,
Yaginuma Hiroyuki
Publication year - 2013
Publication title -
congenital anomalies
Language(s) - English
Resource type - Journals
eISSN - 1741-4520
pISSN - 0914-3505
DOI - 10.1111/cga.12019
Subject(s) - myotome , anatomy , semaphorin , dorsal root ganglion , biology , axon , dorsum , neuroscience , sensory system , embryo , embryogenesis , microbiology and biotechnology , somite , receptor , biochemistry
The spinal nerve, which is composed of dorsal root ganglion ( DRG ) sensory axons and spinal motor axons, forms the dorsal ramus projecting to the dorsal musculature. By using the free‐floating immunohistochemistry method, we closely examined the spatiotemporal pattern of the formation of the dorsal ramus and the relationship between its projection to the myotome/dorsal musculature and semaphorin 3 A ( Sema3A ), which is an axonal guidance molecule. In embryonic day ( E ) 10.5– E 11.5 wild‐type mouse embryos, we clearly showed the existence of a waiting period for the dorsal ramus projection to the myotome. In contrast, in E 10.5– E 11.5 Sema3A ‐deficient embryos, the dorsal ramus fibers projected beyond the edge of the myotome without exhibiting the waiting period for projection. These results strongly suggest that the delayed innervation by dorsal ramus fibers may be caused by Sema3A‐induced axon repulsion derived from the myotome. Next, by performing culture experiments, we confirmed that E 12.5 mouse axons responded to Sema3A ‐induced repulsion. Together, our results imply that Sema3A may play a key role in the proper development of the dorsal ramus projection.