Bulbourethral Glands

The bulbourethral glands, also known as Cowper’s glands, are a pair of small exocrine glands in the male reproductive system that secrete a clear, mucus-like fluid during sexual arousal. These glands are homologous to Bartholin's glands in females. Their secretion contributes to the pre-ejaculate and functions to neutralize acidic urine residue in the urethra, providing a favorable environment for spermatozoa. The glands are embedded within the deep perineal pouch and are closely related to the membranous portion of the urethra.

Structure

Each bulbourethral gland is a round or ovoid gland with a compound tubuloalveolar structure. Despite their small size, they have a significant secretory role. The glands are composed of numerous secretory lobules which drain into a single excretory duct that opens into the spongy urethra.

• Number: Two (left and right)
• Size: ~6–10 mm in diameter
• Type: Compound tubuloalveolar gland

Histology

• Epithelium: Columnar or cuboidal in secretory acini
• Stroma: Surrounded by smooth muscle and connective tissue capsule
• Ducts: Lined by pseudostratified columnar epithelium, eventually opening into the penile urethra

Location

The bulbourethral glands are located in the deep perineal pouch, posterolateral to the membranous urethra. They lie superior to the bulb of the penis and are surrounded by fibers of the external urethral sphincter. Their ducts pierce the perineal membrane and open into the proximal portion of the spongy urethra (bulbar urethra).

Function

• Pre-ejaculate Secretion: Releases clear mucus before ejaculation to lubricate the urethra and glans penis
• Neutralization: Helps neutralize residual acidic urine in the urethra, creating a safer environment for sperm
• Sperm Protection: Forms part of the first fluid to enter the urethra, reducing friction and potential damage to sperm

Ducts

• Length: ~2.5 cm
• Path: Pierces perineal membrane → opens into the bulbar urethra
• Number: Usually one duct per gland, but may have accessory branches

Blood Supply

• Arterial: Branches from the internal pudendal artery (especially perineal and bulbourethral branches)
• Venous: Drains into the perineal venous plexus → internal pudendal vein

Lymphatic Drainage

• Drains into internal iliac lymph nodes

Innervation

• Autonomic: Pelvic plexus (inferior hypogastric plexus)
• Sympathetic: Promotes ductal contraction during ejaculation
• Somatic fibers: Pudendal nerve (motor innervation to perineal muscles surrounding the gland)

Embryology

• Develop from the urogenital sinus (endodermal origin)
• Homologous to Bartholin’s glands in females
• Fully formed by the third trimester

Clinical Significance

• Cowper’s Gland Cyst: Obstruction of the duct may lead to retention cysts and discomfort
• Bulbourethral Abscess: Infection may present with painful perineal swelling and dysuria
• Cowperitis: Inflammation due to STIs such as gonorrhea or chlamydia
• Urethral Stricture: Scarring of the spongy urethra can block duct openings, affecting secretion flow
• Role in Vasectomy: Though not directly altered, the presence of secretion post-vasectomy can cause diagnostic confusion if not sperm-free