Definition of blastula in US English:



  • An animal embryo at the early stage of development when it is a hollow ball of cells.

    Also called blastosphere
    • ‘Gastrulation in its broadest sense is the reorganization of the cells of the blastula to form a multilayered embryo, the gastrula.’
    • ‘How is it possible that in the past six months, this microscopic blastula has transformed into a being with its own organs, spinal cord and brain?’
    • ‘Embryos treated at lower concentrations showed delayed gastrulation and those treated at higher concentrations developed to blastulae having abnormal blastocoels with excess cells.’
    • ‘A lot of research has gone into answering that, and determining the earliest stage at which the blastula breaks symmetry.’
    • ‘With time, cells gradually become determined, so that similar cells taken from later-stage blastulas and early gastrulas develop according to their fate at the time of transplantation.’


Late 19th century: modern Latin, from Greek blastos ‘sprout’.