Tending the Testes 

What am I looking at?

This is a cross section through multiple testes from a mouse. The gray ovals are Sertoli cells, which form a protective barrier around developing sperm cells (1). The green dots/ovals are sperm (2). The red circles are the nuclei of the Sertoli cells, sperm, and other cells that make up the rest of the testes (3). The blue around the outside of each testis is a tracer that allows the researchers to outline the structures (4).

Biology in the background

The testes are where sperm cells are made. A human male can produce between 70 million and 150 million sperm each day. However, while these sperm are developing, they are fragile and susceptible to damage or death from force, chemicals, and other environmental factors. Therefore, the testes have specialized cells that form a tight protective barrier around the area where the sperm are produced (1).

The average size of a human testis is around 5 centimeters long, or roughly twice the size of a human thumbnail.

Technique

This image was created using confocal microscopy.