part of part of immediately preceded by immediately preceded by occurrent 2-cell stage stage 3 4-cell stage 4c The embryo is composed of four cells and is surrounded by a fertilization envelope. The second cleavage division has taken place meridional and perpendicular to the first cleavage division. This has produced four blastomeres of equal size, all of which contain both animal and vegetal cytoplasm. UBERON:0007233 ecao_developmental_stage