著者

神宮司 洋一

出版者

The Kitakanto Medical Society

雑誌

北関東医学 (ISSN:00231908)

巻号頁・発行日

vol.28, no.3, pp.185-209, 1978-06-30 (Released:2009-11-11)

参考文献数

46

被引用文献数

1

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On the development of mammalian diaphragm it is generally accepted that the muscle of diaphragm was derived from lower cervical myotomes. In the recent, however, it was described on the diaphragm of xenopus, which was consisted of pars ventralis and pars dorsalis, that the latter one was derived developmentally from the mesoderms of forelimb bud.To compare the origin and migration of muscle of mammalian diaphragm with those of xenopus, the author has investigated the development of mouse diaphragm by means of light and electron microscopy on the embryos aged from 9.25 through 12.5 gestational days. The graphic reconstructions traced from photomicrographs taking from the tinctorially examined serial sections are available for the present study.From these observations the following results are obtained;1) The most part of diaphragmatic premuscle mass arises from the ventral edges of 4th and 5th cervical myotomes at early limb bud period (9.75-10.25 gestational days), and secondarily it migrates ventrolaterally toward the dorsal part of transverse septum during at early to late limb bud periods (9.75-11.5 g.d.).2) Only at the late limb bud period (10.5-11.5 g.d.) the diaphragmatic premuscle mass, which was just mentioned in 1), comes into contacts with the proximal border of the mesoderms of forelimb bud, and it appears that the former premuscle mass has received some part of the latter mesoderms during this period. With further development, the diaphragmatic premuscle mass after receiving some part of mesoderms from forelimb bud has migrated far ventral to the transverse septum; thus the contribution of the mesoderm of forelimb bud to the development of diaphragm has been demonstrated in mouse embryos as in xenopus.3) During the process of migrations, the diaphragmatic premuscle mass has mainly consisted of presumptive myoblasts which were characterised by its spindle shapes and numerous free ribosomes with no detectable myofibrils in their cytoplasms.Appearance of myoblasts containing myofibrils is proven in the transverse septum firstly at the later stage (12.5 g.d.) when the premuscle mass has arrived its definitive sites.