GLOSSARY

Meiosis is a special type of cell division that occurs only in germ cells in the testes and ovaries and produces the sex cells (gametes), namely sperm and eggs.
In meiosis the chromosome number is halved; each human gamete has 23 chromosomes, so that after fertilization the resulting cell again has 46 chromosomes.

Stages and Features

Meiosis consists of two successive divisions, meiosis I and meiosis II, and in the end four cells are produced from one original cell.
In meiosis I, homologous chromosomes pair up and exchange segments of DNA, a process called crossing over; the pairs are then separated randomly.
These two phenomena give each gamete a unique genetic combination.