Centrifugation of 2-cell mouse ova: cytoplasm stratification and recovery.

Two-cell mouse ova, which were centrifuged for l h at 70 000-90 000xg, showed a precise stratification of the cytoplasm and an elongation of the nucleus. The ova were fixed at different times and observed by light and electron microscopy using cytochemical methods and detergent extractions. Within 40 min after centrifugation the normal-looking morphology was recovered except for the persisting lipid caps at the centripetal poles of the blastomeres.