Gamete Formation in Plants

• In plants, events such as spore formation may occur between meiosis and gamete formation.
• Haploid spores germinate into haploid gamete-producing bodies.
• Gamete-producing bodies and spore-producing bodies develop during the life cycle of plants.

Gamete Formation in Animals

Germ cell (2n) become primary spermatocytes (2n) which undergo MEIOSIS I to form two secondary spermatocytes (n) which undergo MEIOSIS II to become four spermatids (n).

Spermatids change in form. Each develops a tail to become a mature sperm.

This animation (Audio - Important) describes spermatogenesis.

In females, meiosis and gamete formation are called oogenesis. A germ cell (2n) becomes a primary oocyte (2n) which undergoes MEIOSIS I to form a secondary oocyte (n, and large in size) plus a polar body (n, and small in size). This is followed by MEIOSIS II in which one large ovum (n) plus three polar bodies (n, small) are formed.

The single ovum is the only cell capable of being fertilized by a sperm. The polar bodies wither and die.

This animation (Audio - Important) describes oogenesis.

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