In vitro studies on normal and pathological preimplantation development. I. Events of normal mouse preimplantation development as revealed by microcinematography.

After briefly presenting the main historical data of in vitro culture of preimplantation mouse embryos and their filming, the first own observations on normal preimplantation development made by using microcinematography are presented: development from two-cell to eight-cell embryos; compaction and cavitation. The timing and the duration of various developmental events were recorded. Own observations were compared with previous cinematographic data reported by other authors. Some processes needing further investigations are evidenced: rotation within the zona pellucida, penetration of cytoplasmic emissions through the zona, contraction and reexpansion.