Male Reproductive System: Accessory Glands

The lecture focuses on the accessory glands of the male reproductive system.
These glands are crucial as they contribute most of the fluid in semen.
Three accessory glands: seminal vesicles, prostate gland, and bulbourethral glands.
The lecture will cover their structure and function.

There are two seminal vesicles, each about 5 cm long.
They are active secretory glands that produce a significant amount of fluid.
Contribution: Approximately 60\% of semen fluid comes from the seminal vesicles.
The fluid is mucus-like and alkaline.

The alkalinity helps neutralize the acidic environment of the female reproductive tract (vagina, cervix).
Protection: Neutralizing the acidity protects sperm from damage.
Location: Seminal vesicles are situated on the posterior wall of the bladder.

Fructose:
- Produced by cells lining the seminal vesicle gland.
- Acts as an energy source for sperm motility.
Prostaglandins:
- Special proteins that bind to smooth muscles in the male and female reproductive systems.
- Stimulate muscle contraction.
- Contribute to sperm motility and viability.
Fibrinogen:
- A protein that coagulates semen, forming a solid mass or plug.
- The coagulation helps protect sperm by bringing them together.
- Protection lasts while the alkaline fluid neutralizes the acidic environment in the female reproductive tract.
The fluids are released at ejaculation, a process also known as emission.

The prostate gland is a singular, donut-shaped gland.
The urethra passes through the hole in the middle of the prostate.
Location: Situated immediately underneath the bladder.
Urine from the bladder empties into the prostatic urethra, as does fluid from the seminal vesicles and ductus deferens.

Composed of 30 to 50 tiny glands that connect to form the prostate.
Each gland has a duct that empties into the prostatic urethra.
Fluid made in these glands exits into the prostatic urethra.
That prostatic fluid mixes with fluids from the seminal vesicles and ductus deferens.
Smooth Muscle: The prostate contains smooth muscle that contracts, helping to expel fluid at ejaculation, and prostaglandins can trigger the contraction.

Grows slowly until puberty.
From puberty to age 30, rapid growth occurs, requiring a lot of fluid due to sperm production.
Ages 30 to 45: Growth becomes gradual.
After age 45 it may increase in size.
That increase in size can be normal or may cause issues.
Problems arise if it grows inward towards the prostatic urethra.
Inward growth can block urine flow, and may be problematic.
Prostate cancer can spread and impact urine flow.

Citric Acid:
- Energy source for sperm.
Proteolytic Enzymes (Fibrinolysin):
- Digest proteins and break down the coagulate formed after ejaculation.
- Important for sperm to break free and swim into the cervix and uterus after the vaginal environment is neutralized.
Prostate-Specific Antigen (PSA):
- A protein used in blood tests to detect prostate enlargement.
- High PSA levels may indicate the need for further examination.
Seminal Plasmin:
- An antibiotic that prevents bacterial infections in the male and female reproductive systems.
- Minimizes bacterial growth which would otherwise break down sperm.

The release of mucus neutralizes any acid in the urethra due to prior urine passage.
The thick mucus has lubricating properties.
Aids the flow of ejaculate through the urethra.

Semen is a combination of sperm and fluid from the seminal vesicles and prostate.
Bulbourethral glands contribute a smaller amount.

If the semen sample does not meet the WHO standards, the male may have reduced fertility or be infertile.
Semen analysis tests are common when couples struggle to conceive.

Normal sperm have a defined head, acrosome, and tail.
Abnormal sperm can have various defects like a small acrosome, massive/small head, two heads/tails, or excess cytoplasm.
A normal semen sample should have at least 4\% of normal-looking sperm.