Bulbourethral gland

The bulbourethral glands, also known as Cowper’s glands, are small exocrine glands of the male reproductive system. They play a key role in lubricating and protecting the urethra during sexual activity.

Anatomy

Location

The bulbourethral glands are located on either side of the membranous urethra, within the deep perineal pouch. They are situated posterior to the membranous urethra and anterior to the external urethral sphincter, embedded in the urogenital diaphragm.

Structure

Each gland is small and pea-shaped, measuring approximately 5 to 8 mm in diameter. They consist of a compact glandular body that connects to the urethra via a short duct. The glandular tissue is surrounded by fibrous connective tissue and smooth muscle fibers that facilitate secretion.

Relations

• Urethra: The ducts open into the proximal portion of the penile urethra, allowing secretions to enter directly.
• Prostate: Located inferior to the prostate gland.
• Pelvic Floor Muscles: Embedded in the urogenital diaphragm, providing structural support.

Histology

The bulbourethral glands are composed of mucous-secreting epithelial cells organized into tubuloalveolar structures. Surrounding connective tissue and smooth muscle fibers aid in expelling secretions during sexual arousal.

Development and Embryology

The bulbourethral glands develop from the urogenital sinus during embryogenesis. Their formation begins around the 12th week of gestation and continues to mature throughout fetal development.

• Origin: Derived from endodermal tissue of the urogenital sinus.
• Timeline: Initial bud formation occurs in the first trimester, with ductal connections established by mid-gestation.
• Clinical Relevance: Developmental anomalies such as agenesis, hypoplasia, or cyst formation can affect urinary and reproductive function in males.

Innervation and Blood Supply

Innervation

The bulbourethral glands receive autonomic innervation primarily from the pelvic plexus. Parasympathetic fibers stimulate glandular secretion during sexual arousal, while sympathetic fibers help regulate smooth muscle contraction for expelling secretions.

Blood Supply

Arterial blood supply is provided mainly by branches of the internal pudendal artery, including the artery to the bulb of the penis. Venous drainage occurs through the internal pudendal veins, which drain into the internal iliac veins, ensuring efficient circulation and glandular function.

Function

Secretion

The primary function of the bulbourethral glands is the production of a clear, mucous pre-ejaculate. This secretion lubricates the urethra and prepares it for the passage of semen.

Physiological Role

• Lubrication of the urethra to facilitate smooth passage of sperm during ejaculation.
• Neutralization of residual acidic urine in the urethra, creating a favorable environment for sperm survival.

Contribution to Fertility

By providing lubrication and neutralizing acidity, the bulbourethral gland secretions protect sperm from damage, thereby supporting male fertility and successful reproduction.

Clinical Significance

Common Disorders

• Cowperitis: Inflammation of the bulbourethral glands, often caused by bacterial infection, leading to pain and urethral discomfort.
• Cysts: Blockage of the ducts may result in cyst formation, which can cause swelling or urinary obstruction.
• Obstruction: Ductal blockage can interfere with glandular secretion, potentially affecting lubrication during sexual activity.

Symptoms and Diagnosis

Patients with bulbourethral gland disorders may present with perineal pain, urethral discharge, difficulty urinating, or discomfort during sexual activity. Diagnosis typically involves clinical examination, imaging studies, and sometimes laboratory tests to identify infection or obstruction.

Treatment and Management

• Antibiotics for bacterial infections.
• Surgical drainage or excision for persistent cysts or obstructed glands.
• Supportive care including pain management and monitoring of urinary function.

Imaging and Diagnostic Considerations

Imaging plays an important role in evaluating the bulbourethral glands, particularly when clinical findings are ambiguous or complications are suspected.

• Ultrasound: Useful for detecting cysts, ductal obstruction, and gland enlargement.
• MRI: Provides detailed visualization of glandular structure, surrounding tissues, and potential lesions.
• CT Scan: Occasionally used to evaluate complex perineal or pelvic pathology involving the glands.
• Differential Diagnosis: Imaging helps differentiate bulbourethral gland pathology from other periurethral or pelvic lesions, including prostate or urethral disorders.

Surgical and Therapeutic Interventions

Indications for Surgery

Surgical intervention may be required for persistent cysts, abscesses, or ductal obstruction that does not respond to conservative management. Indications include recurrent infection, significant urinary obstruction, or chronic discomfort.

Techniques

• Cyst Drainage: Minimally invasive drainage of obstructed ducts or cysts under local or general anesthesia.
• Excision: Complete surgical removal of the gland may be necessary in rare, severe cases.
• Postoperative Care: Includes monitoring for infection, urinary function assessment, and pain management to ensure full recovery.

Variations and Anatomical Anomalies

The bulbourethral glands can exhibit variations in size, number, and anatomical location, which are important considerations for urologists and surgeons.

• Size and Number Variations: Some individuals may have asymmetrical glands or accessory lobes.
• Congenital Absence: Rare cases may involve complete agenesis of one or both glands, potentially affecting lubrication.
• Duplication: Additional ductal structures may be present, which can complicate surgical or diagnostic procedures.
• Clinical Implications: Awareness of these variations is essential to avoid inadvertent injury during urological surgery or catheterization.

References

1. Standring S. Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 42nd ed. London: Elsevier; 2020.
2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. 9th ed. Philadelphia: Wolters Kluwer; 2021.
3. Drake RL, Vogl W, Mitchell AWM. Gray’s Atlas of Anatomy. 2nd ed. Philadelphia: Elsevier; 2020.
4. Netter FH. Atlas of Human Anatomy. 7th ed. Philadelphia: Elsevier; 2018.
5. Neumann DA. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 4th ed. Philadelphia: Elsevier; 2017.
6. Campbell MF, Walsh PC. Campbell-Walsh Urology. 12th ed. Philadelphia: Elsevier; 2020.
7. Hopper RA, Snyder JA. Anatomy and Clinical Relevance of the Bulbourethral Glands. J Urol. 2019;202(2):310-318.
8. Wein AJ, Kavoussi LR, Partin AW, Peters CA. Campbell-Walsh-Wein Urology. 12th ed. Philadelphia: Elsevier; 2020.