Sperm and Semen

Sperm, also known as sperm cells or spermatozoa are the male sex cells or gametes. These cells are produced in the testes by a process of meiotic division called spermatogenesis. Sperm are very small and lack most typical organelles. Additionally, sperm are the only human cells that have a flagellum.

Each sperm cell has three regions:

  1. Head- contains the nucleus with the male’s genetic contribution to a new organism and the acrosome. The acrosome is a lysosomal like organelle that assists fertilization.

  2. Midpiece- consists of many mitochondria that use the nutrients in the seminal fluid to make ATP to power movement of the tail.

  3. Tail- a flagellum that moves the cell to the site of fertilization.

Figure 1: A labeled illustration of a sperm cell.

Semen is the fluid that leaves the body during ejaculation. Semen has 2 parts:

  1. Sperm

  2. Seminal fluid- supporting secretions from the seminal vesicles, prostate gland, and bulbourethral glands.