vitelline membranes การใช้

• These contents digest the jelly coat and eventually the vitelline membrane.
• Different taxa show different cellular and acellular envelopes englobing the vitelline membrane.
• The mucopolysaccharides attract water to raise the vitelline membrane.
• Through these molecules the vitelline membrane is transformed into the fertilization membrane or fertilization envelope.
• The sperm binds to the egg through another ligand reaction between receptors on the vitelline membrane.
• The sperm surface protein bindin, binds to a receptor on the vitelline membrane identified as EBR1.
• The proteases cleave the bridges connecting the plasma membrane and the vitelline membrane and cleave the bindin to release the sperm.
• In the cortical reaction, cortical granules directly beneath the plasma membrane are released into the space between the plasma membrane and the vitelline membrane ( the perivitelline space ).
• The hyalin forms a layer adjacent to the plasma membrane and the peroxidases cross-link the protein in the vitelline membrane to harden it and make it impenetrable to sperm.
• The zona pellucida, a thick layer of extracellular matrix that surrounds the egg and is similar to the role of the vitelline membrane in sea urchins, binds with the sperm.
• The first envelope-the one in contact with the membrane of the egg-is made of glycoproteins and is known as the vitelline membrane ( zona pellucida in mammals ).
• 2 ) Diffusion must occur in a confined space, if a gradient is to be established however many organisms such as the axolotl develop normally even if the vitelline membrane and jelly layers are removed and development occurs in flowing water.
• This itself triggers the cortical reaction, which results in depositing several substances onto the vitelline membrane through exocytosis of the cortical granules, transforming it into a hard layer called the  fertilization membrane, which serves as a barrier inaccessible to other spermatozoa.