Continued efforts to identify components of the oocyte
that are affected by heat stress and consequences
thereof are important as the matured oocyte contributes
more than 99% of the cytoplasm and half of the
genetic material to the embryo. Results showing that
earlier insemination in vitro prevented heat-induced
reductions in embryo development suggest that effects
of physiologically relevant elevated temperatures on
the oocyte are likely not irreparable. However, because
the bovine oocyte undergoes nuclear maturation and
the majority of cytoplasmic maturation while contained
within the Graafian follicle before ovulation, additional
studies are needed to evaluate the extent to which alterations
in the timing of in vitro fertilization of heatstressed
oocytes affects embryo development, and to
determine the extent to which elevated maternal temperatures
alter specific components in the oocyte matured
in vivo.