Fertility Basics: The Male Reproductive System

Understanding male infertility and gaining a better sense of how fertility complications affect reproductive health means getting to know the various functions of the male reproductive system. An underlying fertility problem can affect any part of the reproductive system, whether reproductive system organs, hormones, or ducts. Being familiar with the male reproductive system is therefore essential to understanding conception.

The Male Reproductive System

The male reproductive system is made up of four major parts. These are the testes, the duct system, the gland system and the penis.

The testicles are the site of both sperm production as well as the production of testosterone hormones. The testes are two oval-like organs and are made up of three components:

  • Seminiferous tubules (hundreds of tiny tubes)
  • Leydig cells where testosterone hormone is produced
  • Sertoli cells which nurture immature sperm cells

The scrotum is the sac in which the testes are stored, and is responsible for protecting and supporting the testicles. In particular, testicles require an atmosphere that is slightly cooler than body temperature. The scrotum helps regulate this temperature. For instance, when exposed to cold air, the scrotum contracts to keep testicles warm, but hangs lower when exposed to hot temperatures.

The Duct System
The duct system of the male reproductive system is comprised of tubes, which function to transport fluids within the male body. These tubes are necessary in order to maintain sperm health and motility. The major components of the duct system are the epididymis, vas deferens and seminal vesicles.

The epididymus is a group of tightly coiled tubes located at the top of the testicles. These tubes are responsible for the temporary storage of sperm as they mature and leave the testicles. The epididymus is also the site where sperm first develop the ability to move.

Vas Deferens
This is a long tube connecting the epididymis to the urethra, the tube responsible for expelling sperm as well as urine from the body, and extends to the head of the penis. The vas deferens is another storage place for sperm, as they await ejaculation.

The Gland System
The gland system is responsible for the secretion of fluids, which in addition to sperm, make up the total volume of semen - the fluid released during ejaculation. These secretions are necessary to fertility since they provide sperm with nourishment and assist sperm motility. The main components of the duct system are:

  • the seminal vesicles are two pouch-like structures located behind the bladder
  • the prostate gland is a walnut-shaped gland that sits below the bladder and is responsible for secretions that make up 60% of semen volume
  • the Cowper's glands are two small glands located below the prostate

The Penis
The penis is an organ largely comprised of blood vessels and spongy tissue, and is made up of three parts: the head, the root and the shaft. When a man is sexually aroused, the arteries dilate and fill the spongy tissue with blood. The penis then becomes erect, allowing for easier intercourse and the ejaculation of sperm.

The Hormones
The major hormones involved in the male reproductive system are: gonadotropin releasing hormone (GnRH), follicle stimulating hormone (FSH), lutenizing hormone (LH) and testosterone.

GnRH is released by the hypothalamus in the brain and signals the production of follicle stimulating hormones as well as lutenizing hormones. LH is responsible for initiating the process of sperm production, while FSH stimulates and maintains sperm production.

Testosterone is produced in the Leydig cells of the testicles and is responsible for sperm maturation as well as sperm production.