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Lesson: Chapter 14 — Continuity of Life

14.3. The male reproductive system 3 of 4

The sperm cell

The process of sperm production is very sensitive to temperature.

For healthy sperm to be formed, the temperature in the testes must be lower than body temperature. This is precisely why the pair of testes is situated outside the body, in a bag of skin called the scrotum — an arrangement that looks careless until you know what it is for.

The structure of a sperm

Mature sperm are motile. A sperm consists of three parts:

  • the head;
  • the middle piece;
  • the tail.

Figure to be added

Figure 14.22 — the electron-microscope structure of a sperm, with the head, neck, middle piece and tail labelled.

Three parts, three jobs

The shape is entirely functional. The head carries the nuclear material that will fuse with the ovum. The middle piece is packed with mitochondria, which supply the energy. The tail spends that energy on swimming. A sperm is a nucleus with an engine and a propeller.