This is a free preview. For full access
Fertilization
Description
Fertilization
Fertilization is the process in which a sperm cell from a male and an egg cell from a female join together to form a new life. This is the first step in the development of a new organism. In animals, fertilization usually happens inside the female’s body, while in ...
Show More
Transcript
Every human life starts from a single cell formed when a sperm combines with an egg, usually in the fallopian tube.
But first, the ovary must release an egg. Each month during ovulation, an ovary releases one mature egg into the fallopian tube, where it can survive for about 24 hours.
If, during sexual intercouse, sperm enter the vagina, they swim toward the fallopian tubes.
When they reach the egg, one sperm may break through its outer membrane and release its nucleus inside. This is when fertilization happens, and the egg’s membrane immediately changes to block other sperm.
Next, the sperm nucleus fuses with the egg nucleus, combining 23 chromosomes from each parent. This forms a zygote with 46 chromosomes, carrying instructions to develop into a human.
The zygote then travels down the fallopian tube, dividing multiple times through mitosis, forming a ball of cells.
When it reaches the uterus, the hollow ball of cells attaches to the uterine lining in a process called implantation, usually happening about a week after fertilization.
From this point, the ball of cells develops into an embryo, and continues its development to become a baby.
Create an account or sign in to view full transcript