What bodily components are required for the synthesis of ejaculated volume?

Components Required for Ejaculate Volume Synthesis

The synthesis of ejaculated volume primarily requires functional seminal vesicles, prostate gland, and bulbourethral glands, with the seminal vesicles contributing approximately 70% of the seminal fluid volume. 1

Anatomical Components and Their Contributions

The male reproductive system requires several key structures to produce normal ejaculate volume:

1. Seminal Vesicles

   • Contribute approximately 70% of the total seminal fluid 1
   • Secrete fructose (>1.2 mg/ml), which provides energy for sperm
   • Produce prostaglandins (>250 μl/ml) and specific proteins like semenogelin
   • Require testosterone for proper development and function 2

2. Prostate Gland

   • Contributes to seminal fluid volume
   • Produces prostate-specific antigen (PSA) which liquefies semen
   • Requires dihydrotestosterone (DHT) for development and function 2

3. Bulbourethral Glands

   • Contribute pre-ejaculatory fluid
   • Help lubricate the urethra during ejaculation 3

4. Epididymis

   • Stores and transports sperm
   • Contributes minimally to overall volume 3

Hormonal Regulation

Proper hormonal function is critical for ejaculate production:

• Testosterone: Essential for development and maintenance of seminal vesicles 4

  • Responsible for normal growth and development of male sex organs
  • Stimulates secretory activity of the seminal vesicles 1

• Dihydrotestosterone (DHT):

  • Regulates semen volume and viscosity 2
  • Critical for prostate and seminal vesicle development
  • Men with 5α-reductase-2 deficiency (unable to convert testosterone to DHT) have extremely low semen volume (0.05-1.0 mL) 2

• Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH):

  • Regulate testosterone production and spermatogenesis
  • Abnormal levels may impact overall reproductive function 5

Clinical Implications

When evaluating low ejaculate volume (<1.5 mL), consider:

• Obstructive Causes:

  • Ejaculatory duct obstruction should be suspected with acidic, azoospermic semen volume <1.5mL, normal testosterone, and palpable vas deferens 6
  • Transrectal ultrasound (TRUS) is recommended for evaluation 6

• Hormonal Causes:

  • Testosterone deficiency
  • DHT deficiency (as in 5α-reductase-2 deficiency) 2

• Congenital Abnormalities:

  • Seminal vesicle agenesis or hypoplasia
  • CFTR gene mutations leading to vasal and seminal vesicle agenesis/atresia 6

Important Considerations

• Normal ejaculate volume ranges from 1.5-5.0 mL according to AUA guidelines 5
• High ejaculate volume (>8.0 mL) can cause "dilution oligozoospermia" where sperm concentration appears low but total sperm count is normal 7
• When evaluating male fertility, at least two semen analyses should be performed at least one month apart due to natural variations 5
• Lifestyle factors including diet, alcohol consumption, smoking, and environmental exposures can temporarily affect semen quality 5

Diagnostic Approach

For patients with abnormal ejaculate volume:

1. Perform comprehensive semen analysis including:

   • Volume (normal: 1.5-5.0 mL)
   • pH (normal: >7.2)
   • Sperm concentration
   • Total motile sperm count 5

2. For low volume (<1.5 mL):

   • Check semen pH (acidic pH suggests ejaculatory duct obstruction)
   • Consider TRUS if ejaculatory duct obstruction is suspected 6
   • Evaluate hormonal status (testosterone, FSH, LH) 5

3. For high volume (>8.0 mL):

   • Consider total sperm output rather than concentration to avoid misdiagnosis of oligozoospermia 7