A new life begins
Fertilisation and implantation.
A tiny first cell
A human life begins from one cell. That cell then divides many times.
Where do you think the first cell forms and where does it settle to grow?
What this lesson covers
The idea
A sperm that reaches the egg in the oviduct and fuses with it forms a zygote, which divides by mitosis while moving to the uterus and implants in its thickened lining; implantation begins pregnancy.
A tiny first cell
A human life begins from one cell. That cell then divides many times.
Where do you think the first cell forms and where does it settle to grow?
- It forms in the oviduct and settles in the uterus
- It forms in the uterus and settles in the oviduct
- It forms outside the body
The journey of the zygote
Press Next step. The picture is a simple schematic.
Zygote to pregnancy
The sperm met the egg in the oviduct and formed a zygote. The zygote divided by mitosis as it moved to the uterus, and then settled into its thick lining. That settling is implantation, and pregnancy begins.
A sperm that reaches the egg in the oviduct and fuses with it forms a zygote. The zygote divides by mitosis while moving to the uterus and implants in its thickened lining. Implantation begins pregnancy.
Notes
A sperm fuses with the egg in the oviduct to form a zygote, which divides by mitosis, reaches the uterus and implants; implantation begins pregnancy.
Check yourself
Where may a sperm meet and fuse with the egg?
How does the zygote divide while it travels to the uterus?
Where does the zygote implant?
What does implantation mark?
- In the vagina. Sperm enter through the vagina, and may reach the egg in the oviduct.
- In the oviduct — correct. Yes!
- In the scrotum. The scrotum is part of the male system, where the testes lie.
- By meiosis. Meiosis forms gametes. The zygote divides by a series of mitotic divisions.
- By budding. Budding is a method of asexual reproduction in organisms like hydra.
- By mitosis — correct. Yes!
- In the thickened inner lining of the uterus — correct. Yes!
- In the ovary. The ovary produces eggs and hormones.
- In the oviduct. The zygote travels through the oviduct to the uterus, where it implants.
- The end of pregnancy. Implantation begins pregnancy.
- The beginning of pregnancy — correct. Yes!
- The release of the egg from the ovary. That is ovulation.