Emergency contraception is sometimes referred to as the “morning after pill” but it can be used for up to 120 hours after unprotected sex. They prevent fertilization and ovulation but do not affect implantation. Most of them contain high doses of female hormones to prevent pregnancy. There are few side effects of these methods, which decrease the pregnancy chances by 85 percent. IUDs are also used as emergency protection and these are more effective than hormones alone.
THE PROCESS OF CONCEPTION The process of conception is referred to as human fertilization in humans. It happens in the ampulla of the fallopian tube and represents the union of the sperm and egg to created a zygote cell. It begins with vaginal sex and ejaculation before or during female ovulation. The major exception to this process is in vitro fertilization or artificial insemination, which do not involve sex but still lead to human fertilization. As you remember from chapter one, the sperm must bind to and fuse with the egg cell or oocyte. The corona radiata surrounds the secondary oocyte and is a layer of follicular cells. There is a drawing out or conical elevation of the yolk or cytoplasm of the egg when the sperm cell is about to pierce the egg. This is also referred to as the reception cone or the cone of attraction. The outside of the yolk changes into a membrane called the perivitelline membrane after the sperm cell has entered. The purpose of this membrane is to prevent more sperm from entering the oocyte. Figure 21 shows the structure of the egg and sperm cell:
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