The Spemann organizer meets the anterior-most neuroectoderm at the equator of early gastrulae in amphibian species.
Bottom Line: However, we found that this physical contact was already established at the equatorial region of very early gastrula in a wide variety of amphibian species.After the contact is established, the dorsal axis is formed posteriorly, but not anteriorly.The model also implies the possibility of constructing a common model of gastrulation among chordate species.
Affiliation: JT Biohistory Research Hall, 1-1 Murasaki-cho, Takatsuki, Osaka, 569-1125, Japan; Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.Show MeSH
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Mentions: Anterior terminal neural tissue is determined when the anterior tip of the axial mesoderm reaches the anterior-most portion of the prospective neuroectoderm at the blastocoel roof. In this work, the establishment of this physical contact is called “anterior contact establishment” (ACE) (cf. Fig. 10A-6). The establishment of physical contact between the organizer and the prospective neuroectoderm is one of the important steps for axis formation. As the prospective head neuroectoderm is known to locate around the animal pole in fate maps of early gastrula (Vogt 1929; Nakamura 1942; Keller 1975), ACE should occur around the animal pole area of mid- to late-gastrula embryo.
Affiliation: JT Biohistory Research Hall, 1-1 Murasaki-cho, Takatsuki, Osaka, 569-1125, Japan; Department of Biological Sciences, Graduate School of Science, Osaka University, Toyonaka, Osaka, 560-0043, Japan.