Develomemt extra credit.docx

Develomemt extra credit.docx - Nina Cornelius Anatomy and...

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Nina Cornelius Anatomy and Physiology 2 Dr. Harris South University 1.What challenges do sperm encounter on the way to the oocyte and what activity during oocyte activation prevents penetration by additional sperm? According to (Martin, 2017) “With too many sperms, an unusually dense cloud surrounds the egg and more than one sperm may penetrate ( polyspermy ). “Only about 1 in 1 million sperm that are ejaculated into the female reproductive system will reach the site of fertilization. Estrogen also relaxes the cervix, causes cervical mucus to become watery and more alkaline, and stimulates uterine contractions – all of which help sperm penetrate and navigate the female reproductive system. Relaxing the cervix allows sperm to pass and reduces a potential physical barrier. Progressive reduction in sperm numbers between insemination and fertilization undoubtedly serves to reduce the risk of polyspermy (Martin, 2017)” . Cervical mucus may prevent sperm from passing into the uterus, but during ovulation when the egg is released from the ovaries, the mucus gets thinner and lower in ph. These changes make the mucus a great transport medium for the sperm, and help the sperm continue traveling. The uterine contractions help to push sperm toward the correct fallopian tube. Polyspermy is prevented by the cortical reaction, in which oocyte vesicles release their sperm-inhibiting contents via exocytosis 2.List and briefly characterize the three trimesters of gestation.
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  • Winter '17
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