口域器官の発生に關する實驗形態學的研究

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It is well established by the experiments of E. ADAMS (1924), STROER (′33), HOLTFRETER (′35), and others that the contact of the oral-ectoderm to the endoderm is essential for the development of the mouth. The presumptive mouth-ectoderm is dependent on the underlying endoderm for the realisation of its potencies, being the anterior wall of the fore-gut the inductor. However, the development of the Urodele teeth still leaves unsettled questions bearing upon the origin of their enamel organ and dentine. Also as to the origin of the thyroid arguments are by no means all completely at one. This paper gives the results of the analysis of the role which the germ layers play in the formation of the teeth and thyroid. The experiments werecarried out on Ranajaponica and Triturus pyrrhogaster by means of transplantation, culture in vitro and vital staining. 1) In Rana the mouth-ectoderm in stage 19 is well determined (Table 1), and the sxis of mouth is fixed as well with regard to its dorso-ventral differentiation. But the mouthectoderm in Triturus taken from stages 16, 23 differentiates neither into mouth nor its derivatives. 2) In Rana, judging from the results of culture-experiments, the anterior wall of fore-gut is an inductor of the mouth, and the mesoderm does not have a part in the process of induction. 3) As to the origin of thyroid the results of experiments differ from those of MARCUS (1930, ′31, ′32), and I am inclined to believe that it is endodermal in origin (cf. KAWAKAMI; ′39, ′40, ′41). 4) The palatine and splenial teeth develop even after the stomodaeal ectoderm has been completely replaced by foreign determined ectoderm. I agree with ADAMS in taking that these two groups of tooth have endodermal enamel organ. 5) The oral region from stage 21 does not contains any mesectodermal cells (Fig. 2), and in spite of that when it was transplanted ventral to liver or heart, some teeth (0-4) can be produced in the graft. 6) The transplantation of the somites of a tail-bud embryo to the posterior site of the eye of the neurula, resulted in inhibition of the growth of the mesectoderm in the anterior region, with the consequent lack of the palatine and splenial teeth on the operated side, concurrent with the one of the Meckel's and anterior part of trabecula cartilage. From these facts of (5)-(6) it may be stated that the dentine of the anterior tooth groups are mesentodermal in origin, while for the development of the palatine and splenial teeth, whose enamel organ are derived from the endoderm, it is essential an existence of the mesectoderm.
社団法人日本動物学会の論文
1941-12-15

口域器官の発生に關する實驗形態學的研究

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