A female can benefit from spawning with males releasing sperm with a low affinity to her eggs under conditions when polyspermy
is a risk.
A key factor for the low efficiency of IVP porcine embryos is the high rate of polyspermy
(TOKESHI et al., 2007), which is directly associated to the amount of sperm at the site of fertilization (FAUSTINI et al., 2010), and also the oocytes quality (SUZUKI et al., 2003).
Development of the competence of bovine oocytes to release cortical granules and block polyspermy
after meiotic maturation.
"To avoid the fatal consequences of polyspermy
, female reproductive tracts have evolved to become formidable barriers to sperm.
Also available was one of his strap-on "Spukakki" machines (think bukkake, involving a woman being ejaculated on by a group of men) that shot scalding wax all over the floor, and assorted throw rugs, furniture, photographs, wide-eyed visitors, and miniature ceramic donkey carts supporting freshly scented homemade candles, alluding to a kind of bestial bukkakephous polyspermy
. These Dionysian love festivals were underscored by an open bar and delicious food, while the so-called Johnny Cash Gallery, acting as narthex to the main room, was used as a showroom for selected artists.
Fertilization in natural populations of the dioecious brown alga Fucus ceranoides and the importance of the polyspermy
The sperm's penetration of the egg, in addition to stimulating the egg's "sperm blocking" mechanism that prevents polyspermy
, also initiates a series of changes that leads to a release of sequestered calcium ions, which in turn start the mechanisms producing the first cell's cleavage.
Zona hardening prevents subsequent sperm from also fertilizing the egg -- a phenomenon called polyspermy
-- which would result in an overabundance of DNA in the developing egg and in most cases cell death.
Indeed, the entrance of sperm into the oocyte causes sequences of calcium oscillations in its cytoplasm, regulating a series of molecular events such as exocytosis of cortical granules, recruitment of maternal mRNA, pronuclear formation, and polyspermy
Sperm density is not as important as the time over which sperm is allowed contact with the egg, which should be a maximum of 2-5 min to prevent polyspermy
. Clavier (1992) evaluated the relationship of sperm concentrations per unit volume of sea water to fertilization rate for the ormer (Haliotis tuberculate), a species that shares a similar depth distribution with pinto abalone (0-20 m).
The quality of matured oocytes is decisive for the fertilization rate, as a result of sperm penetration and complex oocyte changes including cortical granule exocytosis-prevented polyspermy
and oocyte activation for embryonic development [6-8].
Moreover, the high incidence of polyspermy
(Gil et al., 2010) and low cryo-survival of boar sperm (Rodriguez-Martinez and Wallgren, 2010) also create problems for the production of in vitro fertilized embryos in this species.