Desenvolvimento de embriões clones bovinos reconstruídos com Oócitos coletados de animais vivos ou post-mortem

Abstract

The main source of oocytes used as cytoplasm donor for somatic cell nuclear transfer (SCNT) is usually ovaries recovered post-mortem at commercial abattoir. However, such ovaries come from donors with unknown reproductive or nutritional status, what could compromise the oocyte quality. The present study aimed to evaluate the effect of oocyte source, from ovum pick-up (OPU) obtained from live animals or from abattoir obtained from post-mortem animals, on production of SCNT blastocysts, apoptosis and total cells number of SCNT blastocysts. Oocytes were recovered by OPU (OPU group) or from ovaries recovered post-mortem from cows of unknown origin at a local commercial abattoir (Abattoir group). SCNT embryos were reconstructed with in vitro-matured enucleated oocytes from both groups and cultured for 168 h post-activation. In vitro-fertilized (IVF) and parthenogenetic embryos were used as controls. No difference (P>0.05) was found on fusion, cleavage, and blastocysts rates between OPU and Abattoir groups, but SCNT blastocysts of OPU-derived oocytes had similar (P>0.05) apoptosis index to IVF blastocyst in contrast to SCNT blastocysts of abattoir-derived oocytes (P<0.05). The source of oocyte for SCNT has low impact on blastocyst yield. However, it can influence the abundance of specifics transcripts stored in the ooplasm after in vitro maturation and can have an effect on embryo apoptosis.