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How does the scrotum help maintain conditions needed for sperm production?

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Diagram comparing reproductive pathways: arrows show sexual reproduction forming a diploid zygote from oocyte and sperm, haploid parthenogenesis forming a haploid individual, and two types of diploid parthenogenesis-automixis and apomixis-both resulting in diploid individuals. Symbols indicate haploid and diploid stages. — Animal reproductive system The process of sexual reproduction and several forms of parthenogenesis.

The primary function of the scrotum is to maintain the testes at a temperature several degrees below normal body temperature, which is essential for the production of viable sperm.1

The scrotum regulates temperature through several mechanisms:

Physical Positioning: By protruding from the body wall, the scrotum facilitates cooling. It relaxes and elongates in warm conditions to increase surface area and air circulation, while it contracts in cold conditions to pull the testes closer to the body to conserve heat.1
Muscular Action: The dartos muscle in the scrotal wall and the cremaster muscle, which surrounds the spermatic cord, work to adjust the position of the testes relative to the body.12
Vascular Cooling: In species where the scrotum remains tight against the body, cooling is achieved through an intricate blood system. A network of vessels known as the pampiniform plexus allows warm blood entering the testis to be cooled by the cooler blood exiting it.12

Failure to maintain these lower temperatures can lead to temporary or permanent sterility.12