Cowper gland

ANATOMY: Paired, ~1 cm, pea-sized glands embedded in the deep perineal pouch (deep perineal space), within the external urethral sphincter (sphincter urethrae) muscle, posterolateral to the membranous urethra. Their ducts (~2.5 cm) pierce the perineal membrane and open into the proximal part of the bulbar (spongy/penile) urethra. Homologue of the greater vestibular (Bartholin) glands in females.

EMBRYOLOGY: Develop from endodermal outgrowths of the urogenital sinus (pelvic urethra) under the influence of dihydrotestosterone (DHT, via 5-alpha-reductase). Note that the seminal vesicles, ampulla of the vas, and epididymis derive from the mesonephric (Wolffian) duct, whereas the prostate and bulbourethral glands derive from the urogenital sinus.

HISTOLOGY/FUNCTION: Compound tubuloalveolar mucous glands. Secrete a clear, viscous, alkaline mucus-rich pre-ejaculate (pre-cum) during sexual arousal. This (1) lubricates the urethra, (2) neutralizes residual acidic urine, protecting sperm, and (3) contributes a small portion of the ejaculate volume. Under parasympathetic control (pelvic splanchnic nerves, S2-S4) during arousal. Pre-ejaculate typically contains no sperm, though it may carry sperm remaining from prior ejaculation, which is one reason withdrawal has a significant failure rate.

BLOOD SUPPLY/INNERVATION: Artery to the bulb of the penis (branch of internal pudendal artery). Nerves via the pudendal nerve and the prostatic plexus (autonomic).

CLINICAL SIGNIFICANCE: - Cowperitis: inflammation of the glands, often associated with urethritis (e.g., gonorrhea, chlamydia); can cause perineal pain, dysuria, and abscess formation. - Cowper gland syringocele: cystic dilation of the duct; can cause obstructive voiding symptoms, especially in children. - Gonococcal infection can involve the bulbourethral glands. - Urethral anatomy high-yield: Prostatic urethra → membranous urethra (the narrowest and least distensible part besides the external meatus, surrounded by the external urethral sphincter, with Cowper glands lateral) → spongy urethra. Bulbourethral glands lie near the membranous urethra; straddle injury or pelvic fracture may rupture the bulbar urethra (below the urogenital diaphragm/perineal membrane), with extravasation of urine into the superficial perineal pouch, potentially tracking into the scrotum and penis, and up the abdominal wall under Scarpa fascia. Membranous urethral rupture (pelvic fracture) causes extravasation into the deep perineal pouch and a high-riding prostate. - Ejaculation sequence (Point and Shoot): Emission = sympathetic (T10-L2, hypogastric nerve), Expulsion = somatic (pudendal nerve S2-S4, bulbospongiosus contraction), Erection = parasympathetic (S2-S4), and Cowper glands secrete during the parasympathetic phase. - Mnemonic: "Cowper = Clear lubricant, Caudal to the prostate, in the deep perineal pouch."