Ejaculatory Duct

The ejaculatory ducts are two short tubular structures within the male reproductive system that serve as the final common pathway for sperm and seminal fluid before entering the prostatic urethra. Each ejaculatory duct is formed by the union of the duct of the seminal vesicle and the terminal part of the vas deferens. These paired ducts pass obliquely through the posterior aspect of the prostate gland and open into the prostatic urethra at the seminal colliculus. Their anatomical positioning, development, and function are key to proper ejaculation and fertility.

Structure

Each ejaculatory duct is a slender tube with a narrow lumen and is approximately 1.5 to 2.5 cm in length. It is lined by pseudostratified columnar epithelium and surrounded by a thin layer of smooth muscle that facilitates propulsion of seminal contents into the urethra during ejaculation.

• Number: Two (left and right)
• Length: Approximately 15–25 mm
• Diameter: Narrow, around 0.5–1 mm

Wall Composition

• Epithelium: Pseudostratified columnar cells with secretory granules
• Muscle: Smooth muscle layer — thin but functional in propulsion
• Adventitia: Loose connective tissue surrounding the ducts within the prostate

Location

The ejaculatory ducts are located within the posterior portion of the prostate gland. Each duct begins at the base of the prostate, where the vas deferens meets the duct of the seminal vesicle, and runs anteromedially through the prostate to reach the posterior wall of the prostatic urethra.

Opening into the Urethra

• Urethral site: Open into the prostatic urethra at the **seminal colliculus**, on either side of the prostatic utricle
• Angle of entry: Oblique, which helps prevent retrograde flow of urine into the ducts

Function

• Semen Conduction: Transmit sperm (from vas deferens) and seminal fluid (from seminal vesicles) into the urethra
• Ejaculation: Contribute to propulsion of semen during the climax via smooth muscle contraction
• Prevent Reflux: Oblique course and sphincter-like compression from prostatic tissue help prevent retrograde flow of urine or semen

Blood Supply

• Arterial supply: Branches from the inferior vesical artery and middle rectal artery
• Venous drainage: Prostatic venous plexus → internal iliac vein

Lymphatic Drainage

• Internal iliac lymph nodes

Innervation

• Autonomic fibers from the inferior hypogastric plexus
• Sympathetic: T12–L2 spinal segments — stimulate contraction during emission/ejaculation
• Parasympathetic: Minimal role

Development

• Derived from the **mesonephric (Wolffian) ducts**
• Fusion of the vas deferens and seminal vesicle duct occurs during the 12th week of gestation

Histology

• Epithelium: Pseudostratified columnar with tall and short cells; some secretory function
• Wall: Lacks a distinct tunica muscularis but contracts via adjacent prostatic muscle fibers

Clinical Significance

• Obstruction: Congenital or acquired blockage (e.g., post-infectious fibrosis, cysts) may lead to low-volume or absent ejaculate and infertility
• Ejaculatory Duct Cyst: May cause painful ejaculation, hematospermia, or infertility; visible on transrectal ultrasound
• Prostate Surgery: Damage to ejaculatory ducts can result in retrograde ejaculation or dry ejaculate
• Ejaculatory Duct Resection: A treatment for duct obstruction or cysts in selected infertility cases