Calcium Release and Development of Heat-Shocked Porcine Oocytes after Nucleus-Ooplasm Reconstruction

Abstract We determined the effect of heat shock (HS) on the alterations of development and calcium releasing capacity of nuclear–ooplasmic reconstructed porcine oocytes stimulated by thimerosal. The non-HS (39°C) and the HS2h (41.5°C for 2 h) matured oocytes were enucleated and their spindles/chromosomes were exchanged between these two groups followed by parthenogenetic activation. In the Control group (Csp-Coop), the non-HS spindle (Csp) was transferred to the non-HS ooplasm (Coop). Blastocyst and cleavage rates were higher in both Csp-HSoop (non-HS spindle transferred to the HS ooplasm) and HSsp-Coop (HS spindle transferred to non-HS ooplasm) reconstructed oocytes, but no difference was detected in the average cell number per blastocyst. However, intracellular calcium concentrations ([Ca2+]i) generally declined (p < 0.05) in the reconstructed HS oocytes, with a greater blastocyst rate after parthenogenetic activation. In the present study, time for the completion of spindle transfer in these oocytes wa...