Early development
Early development


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Early development

2.3 Summary of Section 2

  1. After ejaculation some sperm penetrate the cervical mucus, and on arriving in the uterus become capacitated.

  2. A few sperm swim up the Fallopian tube containing the recently ovulated egg.

  3. In the tube the sperm become activated. This involves changes to the membranes and a change in the swimming pattern.

  4. Enzymes from the acrosome allow the sperm to get next to the egg, by removing follicle cells and digesting a path through the zona pellucida.

  5. The membranes of the egg and one sperm fuse, allowing chromosomes from the sperm to enter the egg.

  6. The egg resumes meiosis.

  7. In cases where ‘natural’ fertilization cannot take place, IVF or GIFT may allow conception.


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