Blastulae is a term used to describe an early stage of embryonic development in animals that follows fertilization. This term is specific to animals since plants have a different type of embryonic development. However, there are several synonyms for the word blastulae that can be used interchangeably. Some of these synonyms include blastocyst, blastomere, and morula. Blastocyst refers to the stage where the embryo has a fluid-filled cavity and has differentiated into two cell types. Blastomere refers to a single cell in the early stages of embryonic development. Morula describes the stage where the embryo has divided into a solid ball of cells before forming the blastulae. These synonyms can all be used to describe the early stages of animal embryonic development.