1? fertilization membrane (not visible) 2 blastomeres (8x in total) 3 first cleavage plane 4 second cleavage plane
English name: Sea urchin Scientific name: Psammechinus sp. Familia: Echinidae Classis: Echinoidea Phylum: Echinodermata Regnum: Animalia
The third cleavage plane is laid perpendicularly to the first two planes (orthogonal; here third cleavage in the same plane as the screen surface). Due to the equal distribution of yolk, all blastomeres have about the same size. To next stage. One stage back.
