The Male Reproductive System

​To create new male contraceptive options, we have to understand the male reproductive system. This primer provides a top-line overview of the core components of men’s reproductive biology.

The terms “semen” and “sperm” are sometimes incorrectly used as synonyms. While they are closely connected, they are not the same. This primer helps explain the differences between the two.

​Puberty, the process in which a human child’s body matures into an adult capable of sexual reproduction. Once a human person completes puberty, they are physically an adult. This includes the desire to have sexual relations, along with the ability to reproduce sexually. Learn more about this pivotal event in male reproduction in this primer.

​The penis is the primary sexual organ that male animals use to inseminate females during sexual intercourse. Learn more about this male genital organ in this primer.

Simply put, testicles are where sperm come from. But how else do testicles play their part in the reproductive system? This primer provides details about those two oval-shaped “balls” on either side of a male’s penis.

The scrotum is a feature of the male reproductive system that hangs from the body at the front of the pelvis, between the legs. Learn more about this multi-layered structure that houses key components of the male reproductive system in this primer.

The urethra is a tube that connects the bladder to the urinary opening for the removal of urine from the body of both females and males, and the conduit in men for semen during sexual intercourse. This primer provides details about this tube.

The vas deferens is part of the male reproductive system used to carry ejaculatory sperm out of the epididymis. It consists of two ducts: the left and right vas deferens connect to each testicle through the epididymis. Learn more about these ducts in this primer.

The epididymis is a set of two coiled tubes (one for each testicle) that connects the testicle directly to the vas deferens. This primer provides more details about this duct system.

The prostate is a walnut-sized gland located between the male bladder and the penis, and sits just in front of the rectum. Learn more about this gland in this primer.

Ejaculation is the discharge of semen from the male reproductive tract as a result of an orgasm. It is the final stage and natural objective of male sexual stimulation, and an essential component of natural conception.​ Learn more in this primer.

The ejaculatory ducts are a part of the male anatomy that allows the flow of sperm from the testes through the reproductive system and eventually out through the urethra. Learn more in this primer.

Also known as Cowper’s glands, the bulbourethral glands are two small glands in the male reproductive system that produce and secrete a pre-ejaculate fluid called Cowper’s fluid, known colloquially as “pre-cum”. This primer provides additional information.

Sertoli cells are a specialized cell type found in the seminiferous tubules of the testes that facilitate the production of new sperm, or spermatogenesis. Learn more in this primer.

In order to initiate fertilization, a sperm must first fuse with the plasma membrane of the female egg cell (known as the zona pellucida) and then penetrate through the membrane to fertilize it. In order to accomplish this, sperm cells go through a process known as the acrosome reaction. This primer provides more details.

Capacitation, generally speaking, is the change sperm undergo in the female reproductive tract that enables them to penetrate and fertilize an egg. Learn more about this critical change in this primer.

​The seminal vesicles contribute between 50-80% of the components found in semen, specifically the late ejaculate fluids that support the successful transfer of sperm out of the body. Learn more about this integral part of the male reproductive system in this primer.