EFFECT OF INCUBATION VOLUME AND EMBRYO DENSITY ON THE DEVELOPMENT AND VIABILITY OF MOUSE EMBRYOS INVITRO

The morphology, cleavage rate and viability of preimplantation embryos from random bred Swiss mice were assessed after culture in different incubation volumes and embryo densities. Decreasing the incubation volume, from 320 to 20-mu-l, significantly increased blastocyst cell number (P < 0.01) and embryo development after transfer (P < 0.01). Increasing the number of embryos incubated per drop from 1 to 16 significantly increased the number of two-cell embryos reaching the blastocyst stage in 5 or 320-mu-l. Culturing embryos in groups significantly increased blastocyst cell numbers in all volumes employed and elevated embryo viability. Such observations are consistent with the hypothesis that the preimplantation mammalian embryo produces a factor(s) which can stimulate its own development. The results of this study have implications for clinical in-vitro fertilization, where embryos are routinely cultured individually in relatively large volumes.