Cryopreservation of mouse embryos at morula/compact stage.

PURPOSE: The objective of this article was to study mouse morula/compact stage embryo postthaw survival rates and postthaw developmental potential. METHODS: Mouse morula/compact stage embryos were classified into 3 substages. Their morphological behavior during the freezing and thawing process were examined. Postthaw survival rates and blastocyst formation rates were compared between the three substages and the pronucleate and the 2-cell stage embryos. Finally, Postthaw fully compacted and late compact embryos were transferred to foster mothers. RESULTS: Blastomeres of early compacting embryos separated from each other during the freezing process, whereas in fully compacted and late compact stages, the blastomeres remain compacted. Fully compacted and late compact stage embryos had higher Postthaw survival rates than other stages, though those were not statistically significant (P > 0.05). These two substages had significantly higher blastocyst formation rates than Postthaw pronucleate and early compacting embryos (P < 0.01). A total of 72 Postthaw fully compacted and late compact embryos were transferred and 20 live offspring were delivered. CONCLUSIONS: After passing early compacting stage, fully compacted and late compact stage mouse embryos have high Postthaw survival rates and significantly higher blastocyst formation rates. Successful cryopreservation of embryos at these two substages has a significant value in embryo selection. The results obtained in this study may provide useful information for human assisted reproductive technology.

Pregnancies achieved after transferring frozen morula/compact stage embryos.

OBJECTIVE: To report two cases of frozen embryo transfers in which embryos were frozen at the morula/compact stage and pregnancies were achieved after transfer. DESIGN: Case report. SETTING: Private assisted reproductive program. PATIENT(S): Two women had transfer of embryos that were frozen at the morula/compact stage. INTERVENTION(S): Human morula/compact embryos were cryopreserved and transferred after subsequent thaw. MAIN OUTCOME MEASURE(S): Embryo survival after thawing and subsequent pregnancy outcome. RESULT(S): Three and five compact embryos were frozen on day 4 for two patients, respectively. In the first case, all three embryos survived after thawing, and all were transferred. In the second patient, three of five embryos survived after thawing, and those three surviving embryos were transferred. Pregnancies were achieved in both patients. The first woman became pregnant with twins and delivered two girls weighing 2,270 g and 2,071 g, respectively. The second patient became pregnant with a singleton and delivered a boy weighing 2,837 g. CONCLUSION(S): Human embryos can be frozen and thawed in the morula/compact stage and achieve normal pregnancy. Advantages of embryo freezing/thawing at the morula/compact stage include the following: [1] compared with earlier embryonic stage freezing, morula/compact-stage embryos provide better embryo selection and [2] it is easier and safer to perform assisted hatching on compact-stage embryos when compared with those from other preimplantation stages.

Prenatal diagnosis of a de novo unbalanced translocation (4p+) following in vitro fertilization.

We report herein a de novo unbalanced chromosome translocation in a fetus resulting from in vitro fertilization technology. Prenatal diagnostic analysis of an amniotic fluid revealed a 46,XX,4p+ karyotype. The origin of the extra material on the short arm of chromosome 4 could not be identified by a variety of banding techniques. However, examination of fetal parts did reveal some dysmorphic features.