Human sperm. Light micrograph of several human sperm cells (or spermatozoa). These are male gametes or sexual reproductive cells. They are motile (capable of movement) and are produced in the testis. Each sperm is about 65 micrometres long and broadly divided into head, neck and tail regions. The pear-shaped head contains the genetic material of the male which fertilizes the female egg (ovum). The tail enables the sperm to swim and reach the ovum. Also seen in the image are salt crystals (dark patches) which have crystallised out of the solution (semen) which carries the sperm. Interference contrast. Magnification unknown.