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Embryology of sea urchin: unfertilized egg

Legend:

1 vitelline membrane

English name: Sea urchin
Scientific name: Psammechinus sp.
Familia: Echinidae
Classis: Echinoidea
Phylum: Echinodermata
Regnum: Animalia

The unfertilized egg is surrounded by a yolk membrane (=vitelline membrane). The yolk material is equally spread over the cytoplasm. Therefore this type of egg is called isolecithal (iso= equal; lecithal = yolk).
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