The neglected morula/compact stage embryo transfer

Abstract

The morula/compact embryos had great value for embryo selection, which significantly reduced the number of embryos needed for transfer.

Clinical outcomes of elective single morula embryo transfer versus elective single blastocyst embryo transfer in IVF-ET

“…We did not investigate morula and blastocyst formation rates. However, according to previous studies, 59.2% of good quality embryos on day 3 developed to good quality embryos on day 4 [17], whereas 47% of good quality embryos on day 3 developed to blastocyst on day 5 [29]. These results suggest that the rate of ET cancellation is lower after morula-stage ET than blastocyst-stage ET.…”

“…On the other hand, some researchers have suggested that blastocyst results in improved selection of developmentally competent embryos compared to cleavage stage embryo, because embryonic genome activation occurs, and embryos with genetic abnormalities have difficulty developing to the blastocyst stage during extended culture [18,24]. In terms of embryo selection, Tao et al [17] suggested that the morula/compact embryo with the activated embryonic genome has better selection value compared to cleavage-stage embryos. Also, Harper reported that the embryo travels to the uterine cavity about 3-4 days after fertilization in mammals [19].…”

“…A good quality embryo day 3 was defined as having more than 7 blastomeres of equal size and less than 20% fragmentation. The quality of morula on day 4 was assessed according to the criteria of Tao et al [17], and the quality of blastocyst on day 5 was assessed according to the criteria of Gardner and Schoolcraft [21]. The eSMET on day 4 or eSBET on day 5 was completed by transferring a single best embryo into the uterine cavity in each group.…”

“…According to the results of a retrospective study that analyzed the outcomes in patients with all 'good' embryos [17], day 4 ET achieved a significantly higher implantation rate compared to day 3 ET (46.4 vs. 21.4%, p<0.01), while the number of embryos transferred on day 4 was significantly lower than day 3. The morula-stage embryo should have similar advantages compared to blastocyst-stage embryo, because it has both the activated embryonic genome [18] as well as better synchronization between embryos and a better uterine environment compared to the cleavage-stage embryo on day 2 or 3 [19].…”

The role of morphological evaluation of oocyte and embryo quality in ART programs (a review)

“…Работами многих авторов показано, что ранняя компактизация и достижение стадии морулы в конце 3-х суток дробления, а также раннее начало процесса кавитации (формирования полостей между клетками морулы) являются благоприятными про-гностическими признаками в отношении хорошего качества эмбриона [38].…”