Penetration of the sperm nuclear filament and subsequent fusion of sperm and egg membranes
The egg membrane
and exoskeleton were not separated from the active metabolizing mass but were assumed to contribute little to mass error because they constitute only a small proportion of overall mass.
Embryonic development up to the trocophore stage occurs within the egg membrane
and corresponds to the typical development described for gastropod molluscs, with elimination of the two polar bodies after fertilization; segmentation is of the spiral type with the formation of micromeres and macromeres.
Sekiguchi (1988) also found that inorganic ions pass freely through the inner egg membrane
. Thus, osmoactive substances secreted by the embryo, but which cannot pass through the inner egg membrane
, are most likely responsible for the slightly higher osmolarity of the perivitelline fluid relative to the outer medium.
The sperm penetrated the stripped eggs immediately, but with drilled eggs they took 30 to 60 minutes to locate the hole, penetrate the egg membrane
and reach the egg interior, Gordon told SCIENCE NEWS.
The eggs stuck fast but could be rolled with an insect pin to remove the egg hull and expose either the vitelline layer or the egg membrane
ingredients: BiovaFlex for joint health products; BiovaDerm for skin care; and BiovaPlex for animal health.
Just as the egg plays a role in controlling sperm penetration, the sperm itself undergoes a complex series of chemical (exocytotic) and morphological changes that permit penetration of the egg envelopes and fusion with the egg membrane
. Classic studies on echinoderms have shown that contact with the egg jelly coat induces exocytosis of the acrosomal vesicle, which releases lysins that dissolve the egg envelopes (see reviews by Colwin et al., 1975; Tilney, 1985; Epel and Vacquier, 1978).
Biova is a market leader for water-soluble egg membrane
ingredients, "increased market interest in our water-soluble branded ingredients and expanded global opportunities are the driving forces behind this agreement," said Matt Stegenga, Biova director of sales and marketing.
The two sets of dividing chromosomes need not have equal numbers of chromosomes so long as the anaphase/telophase II was oriented perpendicular to the egg membrane
. In this case, the equational division of the dyads from both groups would yield 30 chromosomes at the periphery of the egg and 30 in the interior.
Biova LLC, developers of patented Hydro5 technology for water-soluble egg membrane
, has increased the standardized protein profile of its BiovaFlex ingredient to what the company claimed is a market-leading 88%.
Some metals may also affect embryogenesis indirectly; this includes cadmium, which exerts its toxic effects by altering egg membrane