Primary Spermatocytes (DNA Shufflers)

A big, busy cell

When a spermatogonium splits, some new cells grow into primary spermatocytes. They sit a little farther in from the wall of the tiny tubes in the testes.

They are large, round cells. Their big nucleus is full of DNA, bundled into threads called chromosomes.

Copy, shuffle, split

• Copy. First the cell copies all its DNA.
• Shuffle. Matching chromosomes line up and swap little pieces, like trading cards. Now the mix is brand new.
• Split. The cell divides in two. This is the first step of meiosis, a special kind of splitting.

In the end, each sperm cell gets half the DNA, in its own special mix.

Primary spermatocyte quiz