Consequences of heat stress exposure during the first 12 h of meiotic maturation differed depending on how and when bovine oocytes were activated. If heat-stressed oocytes underwent IVF ∼24 h, blastocyst development was less than for respective controls and similar to that obtained for nonheat-stressed oocytes undergoing IVF at 30 h (i.e. slightly aged). In contrast, if heat-stressed oocytes underwent chemical activation with ionomycin/6- dimethylaminopurine at 24 h, blastocyst development was not only higher than respective controls, but also equivalent to development obtained after activation of nonheat-stressed oocytes at 30 h. Developmental differences in chemically activated vs IVF-derived embryos were not related to fertilization failure or gross alterations in cytoskeletal components. Rather, ionomycin-induced calcium release and MAP kinase activity were less in heat-stressed oocytes. While underlying mechanisms are multifactorial, ability to obtain equivalent or higher development after parthenogenetic activation demonstrates that oocytes experiencing heat stress during the first 12 h of meiotic maturation have the necessary components to develop to the blastocyst stage, but fail to do so after fertilization. © 2011 Society for Reproduction and Fertility.
CITATION STYLE
Rispoli, L. A., Lawrence, J. L., Payton, R. R., Saxton, A. M., Schrock, G. E., Schrick, F. N., … Edwards, J. L. (2011). Disparate consequences of heat stress exposure during meiotic maturation: Embryo development after chemical activation vs fertilization of bovine oocytes. Reproduction, 142(6), 831–843. https://doi.org/10.1530/REP-11-0032
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