Male Physical Development. As a male matures from a young boy into a man, there are many important things to Physical Examination: Adolescent Male. May 22, - Physical Development in Boys: What to Expect. Enlargement of the Testicles and Scrotum. A near doubling in the size of the testicles and the scrotal sac announces the advent of puberty. Pubic Hair. Changing Body Shape. Penis Growth. "What Are These Bumps On My Penis?" Fertility. Wet Dreams & Involuntary Erections.