CoachThe male system’s organs:
- the two testes, held outside the body’s warmth in the scrotum — the gamete factories: from puberty on they produce sperm cells continuously, by the hundreds of millions;
- ducts that store and carry the sperm, joined on the way by glands whose fluids feed and carry them — together making semen;
- the penis, through which semen leaves the body — the same organ, on its other duty, carrying urine (Definition 53.3); a valve arrangement keeps the two duties strictly apart.
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Example 57.2 (The sperm cell, up close)
Under the microscope (Definition 29.4), a sperm cell is a cell stripped for travel: a head that is almost all nucleus — the father’s contribution, packed (Remark 29.6) — and a lashing tail. Smallest cell in the body, built to swim, provisioned for days. Production runs from puberty into old age: the male factory is continuous.