Describe the process of fertilization in humans... - SS3 Biology Reproduction In Man Question
Describe the process of fertilization in humans, highlighting the key events that occur during the union of the egg and sperm. How does fertilization lead to the formation of a zygote, and what are the early developmental stages that follow?
Fertilization in humans is the process by which a sperm cell from the male fuses with an egg cell from the female, resulting in the formation of a zygote. This union occurs in the fallopian tube, where the sperm must first undergo capacitation to become fully capable of fertilizing the egg. During fertilization, the sperm penetrates the protective layers of the egg through the process of acrosome reaction, facilitated by enzymes in the sperm's head. Once inside, the sperm's nucleus fuses with the egg's nucleus, forming a diploid zygote. Following fertilization, the zygote undergoes rapid cell divisions through a process called cleavage, leading to the formation of a solid ball of cells known as a morula. The morula then undergoes further differentiation and compaction to form a blastocyst, consisting of an outer layer of cells (trophoblast) and an inner cell mass. The blastocyst subsequently implants itself into the uterine wall, a process known as implantation, and forms a connection with the mother's blood supply, initiating the early stages of pregnancy.
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