Human Reproduction — Part 2: Gametogenesis and the menstrual cycle: visual lesson, ISC Class 12 Biology

Lesson

Gametogenesis

Part 2 — how sperms and ova are made, and how hormones time it.

In this lesson you will

Describe spermatogenesis, spermiogenesis, spermiation and oogenesis
Explain the hormonal control of gametogenesis
Relate ovarian and uterine changes to hormones in the menstrual cycle
Distinguish oestrous and menstrual cycles

Concept

Spermatogenesis

Begins at puberty. Spermatogonia (2n, 46) multiply by mitosis; some become primary spermatocytes (2n), which complete meiosis I to form two secondary spermatocytes (n, 23); these complete meiosis II to form four spermatids (n).

Diagram

The sperm

A sperm has a head with an elongated haploid nucleus capped by the acrosome (enzymes that help fertilise the ovum), a neck, a middle piece with numerous mitochondria (energy for movement) and a tail. A plasma membrane covers the whole body.

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