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What causes slow block of polyspermy?
Slow block of polyspermy In mammals, in which fertilization occurs internally, fewer sperm reach the fertilization site in the oviduct. This may be the result of the female genital tract being adapted to minimize the number of sperm reaching the egg.
What is slow and fast block to polyspermy?
Keep your answer brief. 1) FAST BLOCK = electrical barrier, preventing fusion of sperm p.m. and egg p.m.; Slow Block is mechanical block to polyspermy, i.e. the fertilization membrane., which hardens and is impervious to further sperm.
Which ion controls the slow block to polyspermy?
Together, the fertilization envelope and other changes in the egg’s surface impede the entry of additional sperm nuclei and thus act as a longer-term slow block to polyspermy. calcium ions (Ca2+) in the egg.
Which of the following is involved in slow block to check polyspermy?
– The slow block of polyspermy is physical and is mediated by calcium ions. – Release of calcium ions propagates from the point of sperm entry, causing the cortical granules to fuse with the egg cell membrane.
Which block to polyspermy is long lasting?
Accordingly, it is concluded that the bovine block to polyspermy is both stable and long-lasting when tested in vitro in the presence of freshly capacitated bull spermatozoa.
What causes the slow block to polyspermy quizlet?
In the cortical reaction, cortical granules fuse with the egg cell membrane and release their contents via exocytosis into the space between the vitelline layer and the egg cell membrane. Slow block to polyspermy occurs later in the cortical reaction and involves receptor clipping.
How long does the fast block to polyspermy take to occur?
Part of this time is necessary for the sperm to swim to the egg surface and to attach to the vitelline membrane. Only then does the sperm fuse with the egg plasma membrane. Therefore, it can be concluded that the fast block to polyspermy is established in less than 3 s after fusion of the fertilising sperm.
Can 1 baby have 2 biological fathers?
Unsourced material may be challenged and removed. Superfecundation is the fertilization of two or more ova from the same cycle by sperm from separate acts of sexual intercourse, which can lead to twin babies from two separate biological fathers.
How does theslow block to polyspermy work?
Theslow block to polyspermyin the sea urchin embryo consists of a physical barrier to further sperm penetration into the egg. Cortical granule exocytosis results in the formation of the fertilization envelope (often called the fertilization “membrane”, even though the structure is not a true membrane)
What is the slow block to polyspermy in the sea urchin?
What is the slow block to Polyspermy? The slow block to polyspermy in the sea urchin embryo consists of a physical barrier to further sperm penetration into the egg. Cortical granule exocytosis results in the formation of the fertilization envelope (often called the fertilization ‘membrane’, even though the structure is not a true membrane).
Which is a slow block to polyspermy-cortical granules?
Slow Block to Polyspermy – Cortical Granules. The cortical granules contain enzymes that aid in the detachment of the vitelline envelope, as well as other components that aid the osmotic swelling of the fertilization envelope away from the egg. Cortical granules also contain extracellular matrix proteins that are deposited on the egg surface,…
How is the fast block to poly spermy achieved?
The fast block to poly-spermy is achieved by changing the electric potential of the egg plasma membrane. This membrane provides a selective barrier between the egg cytoplasm and the outside environment, and the ionic concentration of the egg differs greatly from that of its surroundings.