which of these is a hollow ball of cells
Blastocoel and blastoderm. The blastula (from Greek Î²Î»Î±ÏÏÏÏ (blastos), meaning sprout) is a hollow sphere of cells, referred to as blastomeres, surrounding an inner fluid-filled cavity called the blastocoele formed during an early stage of embryonic development in animals. blastula is a sphere of cells surrounding a blastocoele. The blastocoele is a fluid filled cavity which contains amino acids, proteins, growth factors, sugars, ions and other components which are necessary for cellular differentiation. The blastocoele also allows blastomeres to move during the process of gastrulation.