Developmental competence of porcine parthenogenetic embryos relative to embryonic chromosomal abnormalities

Abstract

Parthenogenetically activated (PA) embryos exhibit delayed development, a lower blastocyst rate, and less successful development in vitro compared to in vitro fertilized (IVF) embryos. To investigate the possible mechanisms for unsuccessful parthenogenetic development, this study analyzed the chromosome abnormalities and developmental potential of porcine PA embryos. Mature oocytes were electrically activated and cultured in Porcine Zygote Medium-3 (PZM3) supplemented with 3 mg/ml BSA for 6, 7, or 8 days. The percentage of PA blastocysts was lower than that of IVF embryos on days 6 and 7 (16.4 +/- 7.4 vs. 28.7 +/- 3.7; 10.9 +/- 2.8 vs. 21.5 +/- 4.7, P < 0.05; respectively), and the PA blastocysts had significantly fewer nuclei than IVF blastocysts (23.2 +/- 1.8 vs. 29.7 +/- 0.8; 29.7 +/- 3.3 vs. 32.0 +/- 2.4, P < 0.05). The percentage of abnormal PA embryos (including embryos with condensed nuclei, arrested embryos and fragmented embryos) was higher than that of IVF embryos (PA: 52.9 +/- 12.8 vs. 16.4 +/- 7.4 on day 6), and increased with culture time (71.9 +/- 12.1 vs. 10.9 +/- 2.8. on day 7,and 75.0 +/- 22.6 vs. 12.1 +/- 2.3 on day 8, P < 0.05). The Day-6 PA blastocysts (n = 147) were divided into three classes according to the total number of nuclei (<20, 20-39, >40) and into three groups according to the morphological diameter (<150, 150-180, >180 microm). Of the haploid blastocysts, 56.1% had less than 20 nuclei, and 71.5% were less than 150 microm in diameter. Of all (114) blastocysts suitable for analysis, 55.5% displayed chromosomal abnormalities. Among chromosomal abnormalities in PA blastocysts, haploid blastocysts were most prevalent (43.6%), while polyploidy (4.4%) and mixoploidy (7.7%) embryos were less prevalent. Chromosomal abnormalities of porcine PA embryos might contribute to a higher rate of abnormal embryonic development. We suggest that a careful consideration should be given when using the blastocysts with smaller size, and establishing the optimum culture condition for PA embryos development in vitro.

Self-diploidization of human haploid parthenogenetic embryos through the Rho pathway regulates endomitosis and failed cytokinesis

“…Karyotype analysis showed that all HPs exhibited mixed ploidy, including haploid and diploid cells at the blastocyst stage 10, 11 , indicating that some haploid cells had already undergone self-diploidization before the blastocyst stage. Recently, advances in culture conditions and flow cytometric cell sorting have facilitated the derivation of embryonic stem cells (ESCs) from mammalian haploid parthenogenetic and androgenetic embryos 12–15 .…”

Ploidy Assessment of Porcine Haploid and Diploid Parthenogenetic Embryos by Fluorescent In Situ Hybridization Detecting a Chromosome 1-Specific Sequence, Sus scrofa Mc1 Satellite DNA

“…In contrast, karyotype analysis of parthenogenetic blastocysts derived from 2PB embryos by Hao et al (2006) [14] indicated that the rates of parthenogenetic embryos that have only haploid or diploid cells were over 40%, while the rate of mixoploid embryos having both haploid and diploid cells was only 7.7%. The reason for this discrepancy between our results and the results reported by Hao et al is not clear.…”

Effect of shRNA‐mediated Xist knockdown on the quality of porcine parthenogenetic embryos

“…However, parthenogenetic embryos that develop to the blastocyst stage typically have lower total cell numbers and poor developmental competence compared with fertilized embryos (Chen and Yu, ; Hao et al, ; Hardy and Handyside, ). Previous studies have shown that parthenogenetic embryos cannot develop to term in mammals due to abnormally imprinted Xist expression and failed X‐chromosome inactivation (Cruz et al, ; Liu et al, ; Park et al, ; Wang et al, ).…”