Development of porcine embryos following microsurgical blastomere transplantation

Abstract

The objective of these studies was to characterize the in vitro and in vivo development of porcine embryos following microsurgical blastomere transplantation. In Experiment 1, 60 four-cell embryos recovered on Day 3 of gestation (Day 0 = onset of estrus), were subjected to either blastomere transplantation (micromanipulated; n = 30) or no microsurgical procedure (control; n = 30). Four-cell embryos were cultured in modified Kreb's Ringer bicarbonate medium supplemented with 0.4% bovine serum albumin and 10% bovine calf serum. After 72 h in culture, embryos were stained and the number of nuclei per embryo was determined. Blastomere transplantation had no effect on embryonic development in vitro as the numbers of micromanipulated and control embryos that reached the 12–24 and ≥25 nuclei stages were similar ( P<0.40). In Experiment 2, 64 four- to eight-cell embryos recovered on Day 3 of gestation were distributed across two treatments: control ( n=33) or micromanipulated ( n=31). Micromanipulated embryos each received a single blastomere from a donor embryo at the same stage of development. After culture for 4–5 h, seven recipients which exhibited estrus within 24 h of the donors, received either control or host embryos. Seventy-two hours later, the transferred embryos were recovered from the recipient females, stained and the number of nuclei per embryo was determined. The proportion of micromanipulated and control embryos recovered was not different. In comparison with control embryos, a greater ( P<0.02) proportion of micromanipulated embryos contained <50 nuclei. The mean number of nuclei present in embryos which reached the >100 nuclei stage was greater ( P<0.0004) for micromanipulated than for control embryos (173±20 and 125±4, respectively). While blastomere transplantation appears to have no detrimental effect on development of porcine embryos in vitro, it may reduce the proportion of embryos developing beyond the 50 cell stage in vivo.