Cryopreservation of pronucleate mouse ova: slow versus ultrarapid freezing.

The usefulness of ultrarapid freezing of mouse pronucleate ova was investigated in comparison with slow, programmed freezing. Pronucleate mouse ova were frozen using an ultrarapid method in either 3.5 M dimethylsulphoxide (DMSO), 3.

Sperm phagocytosis by corona cells in a human in vitro fertilization system.

Clumps of corona cells were separated from oocytes at the moment of fertilization control and were subsequently processed and cut into 1-mu sections to study their general morphologic patterns. This study revealed an extensive phagocytosis of spermatozoa by corona cells. Clumps of mural granulosa cells of comparable size, recovered from follicular aspirates and incubated with spermatozoa, did not show the same extent of phagocytotic activity.