Embryology of sea urchin: early gastrula (initial phase) |
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Without labels Legend:
1 ectoderm 2 begin of archenteron 3 endoderm 4 blastoecoel (central) 5 direction of invagination
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English name: Sea urchin Scientific name: Psammechinus sp. Familia: Echinidae Classis: Echinoidea Phylum: Echinodermata Regnum: Animalia
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Blastomeres migrate from the vegetal pole inward during the so-called invagination or gastrulation process (according to the direction of the arrows at 5). In this way the ecto- and endoderm are formed. The endoderm covers the developing primitive gut, called archenteron (arche = original - primitive, enteron = gut). To next stage. One stage back. |