The testes, also known as testicles, are the male gonads. They are housed within the scrotum, a sac-like structure located beneath the penis. The scrotum's primary role is to regulate the temperature of the testes, which is crucial for sperm production.

Each testis is surrounded by the tunica albuginea, a dense connective tissue layer that provides structural support and protection. This layer is covered by an outer serous membrane called the tunica vaginalis, which helps reduce friction between the testes and surrounding structures.

The scrotum, composed of a thin layer of skin, superficial fascia, and muscle layers, provides some physical protection. It is divided into two chambers by the scrotal septum, a fibrous partition, each housing one testis. The dartos muscle in the subcutaneous layer wrinkles the scrotal skin to reduce heat loss. In contrast, the cremaster muscles, made of skeletal muscle fibers, draw the testes closer to the body in response to cold temperatures or during sexual arousal. These thermoregulatory functions help maintain an optimal environment for the testes to function effectively.

The paired testes produce sperm and hormones essential for reproduction, and their optimal functioning is necessary for male fertility.