Events of reproduction occurring from meiotic resumption of the
immature oocyte up to its exit from the second meiotic block following
activation will be revealed. Morphological modifications of the
oocyte during maturation will be related to signal transduction
mechanisms involving primary or secondary messengers. A detailed
view will be addressed to genetic and epigenetic control of oocyte
maturation. At fertilization, reciprocal gamete activation and novel
knowledge related to sperm factor and cascade mechanisms occurring
in the oocyte will be focused. A detailed description of ion currents
occurring during fertilization will depict another point of view
of oocyte activation mechanisms, further supporting for their complexity.
Finally, all basic information related to this short time lapse
will be considered in relation to clinical application of assisted
reproductive technologies. New frontiers, such as stem cells and
cloning technologies, will be analyzed and future applications and
improvements will be hypothesised.