Final answer:
The scrotum is suited to cooler temperatures due to its external location and the presence of the dartos and cremaster muscles, which regulate the distance of the testes from the body to maintain the optimal temperature for sperm production.
Step-by-step explanation:
The scrotum has several features that make it suited to maintain the cooler temperatures required for spermatogenesis. First, the scrotum is located outside of the body, which inherently makes it cooler than the body's core temperature. This external positioning is necessary because sperm become immobile at body temperature, and a drop in temperature of about 2°C below body temperature is required for their viability. Additionally, the scrotum contains muscles such as the dartos and cremaster muscles, which are responsible for adjusting the distance of the testes from the body depending on the external temperature. When it is cold, these muscles contract to pull the testes closer to the body for warmth, and when it is warmer, they relax, allowing the testes to descend away from the body, increasing the surface area of the scrotum for heat loss.
The cremaster muscles act like a muscular net covering each testis, which can raise the testes in colder temperatures to conserve heat. Conversely, the dartos muscle in the scrotum helps to reduce the surface area when contracted, which retains heat. These muscle contractions provide a thermoregulatory mechanism, ensuring the optimal temperature for sperm production and vitality.