Leydig Cells (Testosterone Makers)

Little clusters between the tubes

The testes are full of tiny, coiled tubes. Leydig cells are not inside the tubes. They sit in the spaces between them.

They live in small groups, close to tiny blood vessels. They are roundish cells with a round nucleus.

Inside, they store little drops of fat. That fat is the starting stuff for their hormone.

Sending a hormone message

Leydig cells make a hormone called testosterone. They let it out into the blood vessels nearby.

• It tells the tubes next door to keep making sperm cells, when someone grows up.
• It travels around the body and helps build strong muscles and bones.

Leydig cell quiz