bio 5 - The Process of Conception Successful fertilization...

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11/22/2016 1 The Process of Conception Successful fertilization & birth is not simple Fertilization/conception Nucleus of sperm fuses with nucleus of egg A fertile man produces many millions of sperm, but only one fertilizes egg due to many barriers Has to travel 2000 x its length to reach fallopian tube this distance is comparable to a 6 ft. man swimming 2.25 miles The Process of Conception At ejaculation sperm are not capable of fertilization. Acrosome digestive or hydrolytic enzymes must mature in female reproductive tract before sperm can penetrate zona pellucida or jelly like substance surrounding egg When sperm enters the egg Electrical and chemical properties of ovum change and egg secretes chemical that hardens zona pellucida and destroys receptors Then nuclei are drawn together and chromosomes combine Fertilization causes secondary oocyte to finish meiosis and produce a zygote (fertilized egg) Becoming Pregnant Conception most likely occurs during a 6 day period including ovulation and the 5 days prior to ovulation Sperm can live 4 to 5 days after ejaculation Egg can live 12 to 24 hours after ovulation Enhancing the possibility intercourse just prior to or at ovulation predicting ovulation Mucus Fertile begins when yellow or white sticky discharge begins through “ovulatory” mucus which is clear, stringy and stretchy until cloudy discharge resumes Becoming Pregnant Predicting ovulation Fertility Awareness Methods based on menstrual cycle ovulation-predictor urine tests measure rise in LH in urine before ovulation and can tell best time for conception Man on top position may be optimal for conception especially if woman keeps knees elevated afterward to prevent loss of sperm Have sex every day during most fertile days if man has normal sperm count and every other day if sperm count is low. Unfortunately, not everyone becomes pregnant when they want to - they may be infertile Infertility Diagnosis Defined as inability to become pregnant after one year of unprotected sex or more than 6 months of trying for women who are over 35 Usually recommended that the man be assessed for infertility first because test is easier. Man considered infertile if < 20 million & sterile if < 5 million sperm per milliliter of semen More than 6 million couples in U.S. have problems getting pregnant (10-15% of couples) 40% of the time problem lies in males, 40% in females, and 20% lies in both man and woman Infertility can be emotionally devastating Medical and psychological counseling can be sought to deal with struggle Causes are sometimes complex, hard to determine unidentifiable in 15% Male Infertility Male fecundity or ability to produce offspring depends on size, shape, & motility of sperm Many factors can cause male infertility Structural abnormalities : variocele, undescended testes, infections such as mumps or STIs, & even antibodies against
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