Introduction

Humans reproduce sexually, and are viviparous — giving birth to live young rather than laying eggs. The full sequence runs: gametogenesis (forming sperm in males, ova in females), insemination (sperm delivered into the female reproductive tract), fertilisation (sperm and egg fusing into a zygote), implantation (the resulting blastocyst attaching to the uterine wall), gestation (embryonic development), and finally parturition (delivery). All of this begins only after puberty. But the male and female sides of this sequence differ in real ways — sperm formation, for instance, continues even into old age in men, while ovum formation stops in women by around age fifty. With that sequence in mind, let's look at the male and female reproductive systems in turn.