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| Biggelaar, J.A.M. van den; Edsinger-Gonzales, E.; Schram, F.R.. |
| Recent discoveries in the field of developmental genetics have lead to the resurrection of the old idea, first proposed in the early 19th century, that the dorso-ventral axis of deuterostomes, such as vertebrates, has been inverted during the course of evolution from that noted in protostomes, i.e., what in deuterostomes is dorsal, is in protostomes ventral. However, while attractive in its simplicity, such a suggestion ignores the real events of embryogenesis. During the onset of gastrulation in deuterostomes as well as in protostomes a blastopore is formed with exactly the same embryonic, antero-posterior/dorso-ventral polarity. Subsequent differences in the patterns or morphogenetic movement in gastrulation result in a spatial inversion of this... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Amphistomy; Axis inversion; Deuterostomes; Spiral cleavage; Protostomes; Gastrulation. |
| Ano: 2002 |
URL: http://www.repository.naturalis.nl/record/534350 |
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| Galis, Frietson; Sinervo, Barry. |
| The early stages of organogenesis in metazoans differ drastically between higher order taxa such as phyla and classes. The segmented germ band stage in insects, the nauplius stage of crustaceans, and the neurula/pharyngula stage in vertebrates are examples of this diversification. In striking contrast with this divergence, is the similarity of these stages within these taxa, i.e., within insects, crustaceans, and vertebrates. The early stages of organogenesis, or phylotypic stages, have, thus, remained very similar in most species since the evolutionary origin of the taxa. These phylotypic stages are considerably more similar to each other than to the earlier stages of cleavage and gastrulation. Cleavage and gastrulation stages display not only great... |
| Tipo: Article / Letter to the editor |
Palavras-chave: Evolutionary conservation; Pleiotropy; Cleavage; Gastrulation; Organogenesis; Multicellularity; Phylotypic stage. |
| Ano: 2002 |
URL: http://www.repository.naturalis.nl/record/534407 |
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