Male Reproductive System: Anatomy and Function

• The male reproductive system is composed of four main parts:
  • External genitalia
  • Reproductive organs or gonads
  • Reproductive ducts
  • Reproductive glands

Male External Genitalia

• The male external genitalia consists of the penis and the scrotum
• The penis is a copulatory organ with a long muscular shaft and a bulb-shaped tip called the glans
• The structure of the penis is supported, covered, and protected by the foreskin or the prepuce
• Penile erection is necessary for copulation; it occurs when the male is sexually aroused
• Erection happens because spaces called sinuses within the erectile tissue of the penis fill with blood
• The scrotum is a pouch that hangs behind the penis and is suspended from the pubis
• The scrotum is a continuation of the abdominal wall and is divided into two sacs, each containing and supporting a testis
• The scrotum holds, and protects the testes also contains many nerves and blood vessels

Male Reproductive Organs or Gonads

• The testes are the male reproductive organs or gonads contained inside the scrotum
• Each testis is an oval organ about 5 cm in length
• In early fetal life, the testes lie in the abdominal cavity, then descend into the scrotum about two months before birth
• Each testis contains numerous microscopic coiled tubules called seminiferous tubules
• Formation of sperm cells or spermatogenesis occurs in the seminiferous tubules
• Interstitial cells of Leydig are scattered between the seminiferous tubular tissues
• These cells produce male hormones like testosterones and androgens.

Male Reproductive Ducts

• There is a series of tubular structures that originate initially from the microscopic tubules (seminiferous tubules) that make up the testes
• There are three reproductive ducts found in a male: epididymis, vas deferens, and urethra
• The epididymis is a mass of coiled tubes cupping the posterior aspect of a testis
• The epididymis extends about 3.5 cm from an enlarged anterior end at the top of the testis tapering downward towards the lower back of the testis
• The vas deferens (a.k.a. sperm duct or ductus deferens) is about 30 cm long
• The vas deferens is a continuation of the epididymis that moves up into the pelvic cavity and ascends between the epididymis to enter the abdomen
• This duct lies within the spermatic cord, which also contains blood vessels, nerves, and lymphatic vessels
• The urethra is a tubelike organ that extends from the tip of the urinary bladder to the tip of the penis
• It transports and discharges both urine from the urinary bladder and semen, which contains the sperms

Male Reproductive Glands

• There are three reproductive glands that secrete fluids to complete the semen or seminal fluid:
  • Seminal vesicles
  • Prostate gland
  • Bulbourethral or Cowper's glands
• These glands provide fluids that supply nourishment to the sperm cells and lubrication to the internal duct system
• Seminal vesicles are dilated sac-like structures attached to the ends of the vas deferens and to one side of the urinary bladder
• They contain fructose, and about 70% of the semen is the secretion of the seminal vesicles
• Each seminal vesicle ends in a straight, narrow duct which joins the vas deferens to form a one-inch ejaculatory duct that penetrates the base of the prostate gland and opens into the urethra
• The prostate gland is a conical structure lying below the urinary bladder, surrounding the ejaculatory ducts
• The prostate surrounds the first inch of the male urethra and produces a thin, milky, alkaline fluid, which helps in maintaining the viability of the sperms
• Bulbourethral glands also known as Cowper's glands, are two pea-sized glands located on the sides of the urethra just below the prostate gland
• These secrete a lubricating mucous, a clear, slippery fluid that empties directly into the urethra and serves to lubricate the urethra and to neutralize any acidity that may occur along the length of the male urethra

Seminal Fluid

• Seminal fluid is a slightly alkaline mixture of sperm cells and secretions from the accessory glands
• The volume of semen in a single ejaculation varies from 1.5 to 6.0 ml
• There are usually between 50 to 150 million sperm per milliliter of semen
• Sperm counts below 10 to 20 million per milliliter usually present fertility problems
• Although only one sperm actually penetrates and fertilizes the ovum, it takes several million sperm in an ejaculation to ensure that fertilization will take place

Explore the male reproductive system including the external genitalia, reproductive organs, reproductive ducts, and reproductive glands. Learn about the penis, including its structure and the process of erection. Discover the role of the scrotum in protecting the testes and its components.