The blastocyst stage is characterized by the presence of a blastocyst cavity, outer cell mass and inner cell mass. Embryonic stem cells are derived from the inner cell mass of the blastocyst.

A blastocyst forms about five to six days after a sperm fertilises an egg. Furthermore, high DFI raises the risk of miscarriage.” Dr Sneha Sathe suggested, “If a sperm DFI test reveals high ...

Blastocysts are normally protected from external influences by a coat, the zona pellucida; before the embryo implants in the uterus, the young embryo "hatches" from this protective cover.