English name: Sea urchin Scientific name: Psammechinus sp. Familia: Echinidae Classis: Echinoidea Phylum: Echinodermata Regnum: Animalia
The fertilized egg can be recognized from the presence of a fertilization membrane (=fertilization envelope). This membrane arises after penetration of the first sperm cell into the egg and prevents further fertilization by other sperms. The perivitelline space is located between the fertilization membrane and the yolk. (None of thse two structures is clearly visible in this preparation, but remnants of the fertilization membrane are indicated with 1). To next stage. One stage back.