The cell membrane is the outermost barrier of an animal cell. As for plants, the cell membrane is surrounded by the cell wall, which gives the cell a much more rigid structure. To clarify, all cells have a plasma membrane.
Dec 15, · Sperm-egg fusion is a cell-cell membrane fusion event essential for the propagation of sexually reproducing organisms. In gamete fusion, as in other fusion events, such as virus-cell and intracellular vesicle fusion, membrane fusion is a two-step process.
In mammals complex changes in the plasma membrane of the sperm cell are involved in this process. Sperm cells have unusual membranes compared to those of somatic cells. After leaving the testes, sperm cells cease plasma membrane lipid and protein synthesis, and vesicle mediated rapidshoot.info by:
Echinoderms. The membrane at the tip of the acrosomal process fuses with the egg's plasma membrane. In some echinoderms, including starfish and sea urchins, a major portion of the exposed acrosomal content contains a protein that temporarily holds the sperm on the egg's surface. the plasma membrane of sperm and it is also present in seminal plasma (37). During epididymal transit, an fold increase in the amount of sterol sulfate of the plasma membrane of sperm has been described in hamster (38, 39). This anionic lipid is sequestered into the plasma membrane of the head and of the midpiece of the sperm (40).
fusion of p.m. of oocyte fuses with equatorial segment of fertilizing sperm and is engulfed. cortical granule membranes fused with oocyte plasma membrane and contents of cortical granules are released.
Polyspermy is the double fertilization of an ovum by two sperm. It is prevented by 3 methods during fertilization: 1) The intracellular wave of Ca2+ that travels across the oocyte membrane and causes hyper polarization after fusion of the sperm and oocyte membranes. After the spermatozoa has proceeded through the zona pellucida, the sperm head crosses the perivitelline space and attaches to the cell membrane of the ovum. Subsequently, the sperm and ovum plasma membranes fuse, the sperm enters the ovum, and fertilization follows.
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This depolarization prevents additional sperm from fusing to the egg plasma membrane. The egg plasma membrane is restored to its normal mV potential within minutes of fusion as the Na+ channels close, other + ions flow out of the cell, and Na+ is pumped out. Moved Permanently. The document has moved rapidshoot.info by:
Finally, a single sperm makes contact with sperm-binding receptors on the oocyte’s plasma membrane. The plasma membrane of that sperm then fuses with the oocyte’s plasma membrane, and the head and mid-piece of the “winning” sperm enter the oocyte interior. mammals complex changes in the plasma membrane of the sperm cell are involved in this process. Sperm cells have unusual membranes compared to those of somatic cells. After leaving the testes, sperm cells cease plasma membrane lipid and protein synthesis, and vesicle mediated transport.
Fusion of egg and sperm cell plasma membranes Sometimes steps 2 and 3 are reversed (as in mammalian fertilization) and the sperm binds to the egg before releasing the contents of the acrosome. After these five steps are accomplished, the haploid sperm and egg nuclei can meet, and the reactions that initiate development can rapidshoot.info: Scott F Gilbert.