1. When the egg of Amphioxus is in the Blastosphere stage we cannot speak of either an epiblast or hypoblast

2. A blastocoel, also spelled Blastocoele and blastocele, and also called blastocyst cavity is a fluid-filled cavity that forms in the blastula (blastocyst) of early amphibian and echinoderm embryos, or between the epiblast and hypoblast of avian, reptilian, and mammalian blastoderm-stage embryos.

3. A blastocoel (/ ˈ b l æ s t ə ˌ s iː l /), also spelled blastocoele and blastocele, and also called blastocyst cavity (or cleavage or segmentation cavity) is a fluid-filled cavity that forms in the Blastula of early amphibian and echinoderm embryos, or between the epiblast and hypoblast of avian, reptilian, and mammalian blastoderm-stage embryos.