before vortexing the oocytes (now
presumptive zygotes) to remove cumulus cells and associated
sperm. For this procedure, presumptive zygotes
were removed from F-CDM, placed in H-CDM-1, and
vortexed in 0.5 mL snap-top tubes for 1 minute. Oocytes
were immediately washed from the sides of the tube,
suspended in 200 to 400 mL H-CDM-1, and washed
through seven drops to separate presumptive zygotes
from debris and loose cells. Thereafter, approximately 50
presumptive zygotes were cultured per four-well dish in
500 mL of CDM-1 (modified to contain fructose instead of
glucose) at 38.5 C in an atmosphere of 5% CO2, 5% O2, and
approximately 90% N2 in humidified air. Embryos were
checked for cleavage and developmental status at
approximately 56 hours after vortexing. Noncleaved
oocytes were discarded. Embryos that had only developed
to the two- to five-cell stage were considered retarded
and cultured in a separate well from the more advanced,
normal-appearing embryos with six or more cells. All
embryos were cultured for an additional 4.5 days in CDM-
2 at 38.5 C in 5% CO2, 5% O2, and approximately 90% N2
in humidified air. Embryos in the retarded group only