Final answer:
Testicles typically descend before birth or within the first few months after birth, and in most cases, they should descend by six months of age. If not, a medical consultation is necessary as the condition, cryptorchidism, can lead to health issues.
Step-by-step explanation:
The descent of the testicles into the scrotum is a normal part of male development and typically occurs during the later stages of pregnancy, usually before birth. However, for some infants, this can occur shortly after birth, within the first few months. In most cases, testicles should descend by the time a child is six months old. If a testicle has not descended by six months to a year, a medical professional should be consulted.
The specific condition where one or both testicles have not moved down into the scrotal sac is known as cryptorchidism and can have potential health implications such as reduced fertility or an increased risk of testicular cancer if not treated properly.