Definition of blastula in English:
 blastula
nounPlural blastulae, Plural blastulas ˈblastjʊləˈblæstʃələ
Embryology An animal embryo at the early stage of development when it is a hollow ball of cells.
 Example sentencesExamples
-  A lot of research has gone into answering that, and determining the earliest stage at which the blastula breaks symmetry.
 -  Gastrulation in its broadest sense is the reorganization of the cells of the blastula to form a multilayered embryo, the gastrula.
 -  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.
 -  Embryos treated at lower concentrations showed delayed gastrulation and those treated at higher concentrations developed to blastulae having abnormal blastocoels with excess cells.
 -  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?
 
Origin
  
Late 19th century: modern Latin, from Greek blastos 'sprout'.