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💡 The monthly release
Every month one egg sets out on a journey. If a sperm meets it in time, a new life begins; if not, the body resets and tries again.
What happens from ovulation to implantation?
- From puberty, usually one mature egg is released each month — this is ovulation ; the uterine lining thickens.
- During sexual intercourse, millions of sperm enter and swim up; a sperm may fuse with the egg in the oviduct to form a zygote (Fig. 11.20).
- The zygote divides repeatedly while travelling to the uterus and implants into its lining — marking the beginning of pregnancy.
👤 Meet a Scientist
In-vitro Fertilisation (IVF) is a technique in which an egg and a sperm are combined outside the female body, and the fertilised egg is implanted in the uterus. A baby born this way is commonly called a test tube baby . In 1978, Subhash Mukhopadhyay of Kolkata pioneered India’s first test tube baby, Kanupriya Agarwal (nicknamed Durga), through experimental IVF work.
NCERT Question 3 — Assertion (A): The zygote formed
Assertion (A): The zygote formed after fertilisation immediately attaches to the uterus wall. Reason (R): The uterus wall is always prepared to receive the zygote. (i) Both A and R are true, and R is the correct explanation of A. (ii) Both A and R are true, but R is not the correct explanation of A. (iii) A is true, but R is false. (iv) A is false, but R is true.
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Important Definitions
- Ovulation — the release of one mature egg from an ovary, usually once a month.
- Zygote — the cell formed when a sperm fuses with the egg in the oviduct.
- Implantation — the attaching of the dividing zygote into the thick inner lining of the uterus — the start of pregnancy.
