Summary
Highlights
The male reproductive system is typically viewed from two main perspectives: anterior (front) and sagittal (side, with a cut down the middle). Most of the system is internal, with only the penis and scrotum visible externally. The sagittal view allows for a clear sight of internal structures in relation to each other.
The testes are the key organs, responsible for spermatogenesis (sperm creation) and testosterone production. Sperm production requires a temperature slightly lower than core body temperature, maintained by the scrotum. The cremaster and dartos muscles regulate testicular temperature by retracting or descending the testes. Testosterone drives secondary sexual characteristics like hair growth, muscle development, and voice deepening.
The epididymis, located on top of the testes, is where sperm mature and develop. Here, sperm gain mitochondria for energy and grow flagella for propulsion. From the epididymis, sperm travel through the vas deferens, a tube that carries them upwards behind the bladder and into the urethra. The vas deferens is part of the spermatic cord, which also contains arteries and veins serving the testes.
Accessory glands provide fluids essential for sperm viability and transport. The seminal vesicles contribute about 60% of semen volume with an alkaline, fructose-rich fluid. This fluid neutralizes the acidic environments of the male urethra and vagina and provides energy for sperm. The prostate gland produces prostatic fluid that increases sperm mobility, and the bulbourethral glands secrete a lubricating fluid for the urethra and vagina. Sperm mixed with these fluids forms semen, which then travels through the urethra and the penis for ejaculation.