Ejaculatory Ducts

The ejaculatory ducts are paired short ducts of the male reproductive system that conduct sperm and seminal gland secretions into the prostatic urethra. Each ejaculatory duct is formed by the union of the terminal portion of the ductus deferens with the duct of the seminal gland.

The ducts begin near the posterior aspect of the prostate and pass anteroinferiorly through the prostatic tissue. They terminate by opening into the prostatic urethra on or near the seminal colliculus. Their position places them at an important anatomical junction between the sperm-conducting ducts, the seminal glands, the prostate, and the urethra.

Number

There are normally two ejaculatory ducts, one on the right and one on the left.

Each duct receives sperm from the ipsilateral ductus deferens and secretion from the corresponding seminal gland.

Location

The ejaculatory ducts are located primarily within the prostate.

They begin posterior to or near the posterior surface of the prostate and traverse the gland before opening into the prostatic urethra.

Formation

Each ejaculatory duct is formed by the union of:

• The terminal part of the ductus deferens
• The duct of the seminal gland

This union creates a short common passage through which sperm and seminal gland secretions enter the urethra.

Ductus Deferens

The ductus deferens is a thick-walled muscular duct that transports sperm from the epididymis toward the ejaculatory duct.

After entering the pelvis, it courses toward the posterior surface of the urinary bladder and expands near its terminal portion to form the ampulla of the ductus deferens.

Ampulla of the Ductus Deferens

The distal ductus deferens becomes enlarged to form the ampulla.

The terminal portion of the ductus deferens then joins the duct of the seminal gland to form the ejaculatory duct.

Seminal Glands

The seminal glands, also called seminal vesicles, are paired accessory reproductive glands located posterior to the urinary bladder and superior to the prostate.

Each seminal gland produces a secretion that enters its duct and subsequently joins the sperm-containing fluid carried by the ductus deferens.

Duct of the Seminal Gland

The inferior end of each seminal gland narrows into its excretory duct.

This duct joins the corresponding ductus deferens to form the ejaculatory duct.

Course

After formation, each ejaculatory duct passes anteroinferiorly through the prostate.

The paired ducts converge toward the prostatic urethra and terminate near the seminal colliculus.

Length

Each ejaculatory duct is approximately 2 cm long, although individual anatomical variation occurs.

Its short length reflects the close relationship between the terminal ductus deferens, seminal gland, prostate, and prostatic urethra.

Relationship to the Prostate

The ejaculatory ducts pass through the substance of the prostate gland.

This intraprostatic course is clinically important because abnormalities of the prostate or structures surrounding the ducts can potentially affect ejaculatory duct patency.

Relationship to the Prostatic Urethra

The ejaculatory ducts terminate within the prostatic urethra.

Their openings lie on the posterior wall of the urethra in close relationship to the seminal colliculus and prostatic utricle.

Seminal Colliculus

The seminal colliculus, also called the verumontanum, is an elevation on the posterior wall of the prostatic urethra.

The openings of the ejaculatory ducts are located on either side of the opening of the prostatic utricle in this region.

Prostatic Utricle

The prostatic utricle is a small blind-ending midline recess that opens on the seminal colliculus.

The paired ejaculatory duct openings are positioned lateral to the utricular opening.

Openings of the Ejaculatory Ducts

Each ejaculatory duct opens independently into the prostatic urethra.

The paired openings allow the contents of the right and left reproductive ducts to enter the urethral lumen during ejaculation.

Anatomical Pathway

The pathway followed by sperm from the testis to the ejaculatory duct can be represented as:

1. Seminiferous tubules
2. Straight tubules
3. Rete testis
4. Efferent ductules
5. Epididymal duct
6. Ductus deferens
7. Ampulla of the ductus deferens
8. Ejaculatory duct
9. Prostatic urethra

Continuation Through the Urethra

After entering the prostatic urethra, semen passes through the remaining portions of the male urethra.

The pathway continues through the membranous and spongy portions of the urethra before reaching the external urethral opening.

Function

The principal function of the ejaculatory ducts is to conduct sperm and seminal gland secretions into the prostatic urethra during ejaculation.

They therefore serve as short terminal conduits linking the paired reproductive ducts with the common urinary and reproductive passage formed by the urethra.

Role in Ejaculation

During ejaculation, sperm are propelled from the epididymis through the ductus deferens by coordinated smooth muscle contractions.

The sperm-containing fluid enters the ejaculatory ducts together with secretions from the seminal glands and is discharged into the prostatic urethra.

Emission

Emission is the phase in which sperm and accessory gland secretions are delivered into the posterior urethra.

Contraction of the ductus deferens and accessory reproductive structures contributes to movement of reproductive fluids toward and through the ejaculatory ducts.

Ejaculation

Ejaculation involves expulsion of semen from the urethra through coordinated autonomic and somatic mechanisms.

The ejaculatory ducts participate in the emission pathway by delivering their contents into the prostatic urethra before semen is expelled through the distal urethra.

Contents

The ejaculatory ducts carry a mixture that includes:

• Spermatozoa transported through the ductus deferens
• Fluid accompanying sperm from the reproductive ducts
• Secretions of the seminal glands

Additional secretions, particularly from the prostate, enter the reproductive fluid after the ejaculatory ducts open into the prostatic urethra.

Relationship to Prostatic Secretions

The ejaculatory ducts themselves do not receive the bulk of prostatic secretions.

Numerous prostatic ducts open separately into the prostatic urethra, where prostatic fluid becomes incorporated into semen.

Relationship to the Urinary Bladder

The structures forming the ejaculatory ducts lie posterior and inferior to the urinary bladder.

The ampullae of the ductus deferens and seminal glands are closely related to the posterior surface of the bladder before their ducts converge near the prostate.

Relationship to the Seminal Glands

The seminal glands lie posterior to the bladder and superior to the prostate.

Their inferior ducts descend toward the terminal portions of the ductus deferens, with each pair joining to establish an ejaculatory duct.

Relationship to the Rectum

The seminal glands, ampullae of the ductus deferens, and posterior prostate lie anterior to the rectum.

This anatomical relationship allows portions of the prostate and adjacent structures to be assessed clinically through the anterior rectal wall.

Relationship to the Ureters

Near the posterior aspect of the urinary bladder, each ductus deferens passes superior to the corresponding ureter before approaching the seminal gland.

This relationship occurs before formation of the ejaculatory duct and is an important landmark in male pelvic anatomy.

Wall of the Ejaculatory Duct

The ejaculatory ducts are relatively thin-walled compared with the ductus deferens.

Their walls include a mucosal lining supported by connective tissue and a relatively modest smooth muscle component.

Mucosa

The mucosa of the ejaculatory duct forms the internal lining of the duct.

Its epithelial organization reflects its continuity with the terminal reproductive ducts and its specialized role as a short conducting passage.

Smooth Muscle

The muscular component of the ejaculatory duct is much less prominent than the thick smooth muscle coat of the ductus deferens.

Most forceful propulsion of sperm toward this region is generated by contractions of upstream reproductive ducts, particularly the ductus deferens.

Ductus Deferens versus Ejaculatory Duct

Feature	Ductus Deferens	Ejaculatory Duct
Length	Long	Approximately 2 cm
Wall	Very thick muscular wall	Relatively thin wall
Origin	Continuation of epididymal duct	Union of ductus deferens and seminal gland duct
Course	Scrotum, spermatic cord, inguinal canal and pelvis	Primarily through prostate
Termination	Contributes to ejaculatory duct	Prostatic urethra
Main role	Transport of sperm	Delivery of sperm and seminal gland secretion to urethra

Ejaculatory Duct versus Urethra

Feature	Ejaculatory Duct	Male Urethra
Number	Paired	Single
Primary system	Reproductive	Urinary and reproductive
Urine transport	No	Yes
Semen transport	Yes	Yes
Termination	Prostatic urethra	External urethral opening

Development

The ejaculatory ducts develop from structures derived from the mesonephric ducts.

Under androgenic influence, portions of the mesonephric duct system differentiate into major components of the male reproductive duct system.

Mesonephric Duct

The mesonephric duct, also called the Wolffian duct, contributes to development of the epididymis, ductus deferens, seminal glands, and ejaculatory ducts in the male.

Its persistence and differentiation depend substantially on androgen signaling during development.

Development of the Seminal Glands

The seminal glands arise as lateral outgrowths from the distal mesonephric ducts.

The portion of the mesonephric duct between the developing seminal gland and urethra contributes to formation of the ejaculatory duct.

Autonomic Control

The movement of reproductive tract contents during emission is strongly influenced by the sympathetic nervous system.

Sympathetic activity promotes contraction of smooth muscle within the ductus deferens and accessory reproductive structures, moving sperm and secretions into the posterior urethra.

Sympathetic Innervation

Sympathetic fibers involved in male reproductive tract function reach pelvic reproductive organs through autonomic plexuses.

These pathways are particularly important during the emission phase of ejaculation.

Internal Urethral Sphincter

During ejaculation, smooth muscle near the bladder neck contracts as part of the coordinated autonomic response.

This helps limit movement of semen toward the urinary bladder while reproductive fluids are being delivered into the urethra.

Ejaculatory Duct Obstruction

Ejaculatory duct obstruction is blockage of one or both ejaculatory ducts.

Obstruction can interfere with the passage of sperm and seminal gland secretions into the urethra and may contribute to male infertility.

Causes of Obstruction

Potential causes of ejaculatory duct obstruction include:

• Congenital abnormalities
• Cysts involving the region of the prostate or seminal tract
• Inflammatory changes
• Scarring
• Calculi
• Acquired obstruction following infection or instrumentation

Complete and Partial Obstruction

Ejaculatory duct obstruction may be complete or partial and may involve one or both ducts.

The clinical and semen findings therefore vary according to the extent and location of obstruction.

Effects on Semen

Bilateral complete obstruction can substantially reduce or prevent delivery of sperm through the ejaculatory ducts.

Because seminal gland secretions also pass through these ducts, obstruction can alter characteristics of the ejaculate in addition to affecting sperm delivery.

Obstructive Azoospermia

When both ejaculatory ducts are completely obstructed, sperm production within the testes may remain intact even though sperm are absent from the ejaculate.

This represents a potential distal cause of obstructive azoospermia.

Seminal Gland Dilatation

Obstruction distal to the seminal glands may be associated with dilatation of portions of the seminal tract.

Imaging can therefore be useful when distal reproductive duct obstruction is suspected.

Ejaculatory Duct Cysts

Cystic lesions near the ejaculatory ducts can compress or obstruct their lumina.

Midline and paramedian cystic abnormalities within the prostate may therefore be relevant when evaluating ejaculatory duct obstruction.

Imaging

The ejaculatory ducts and related structures can be assessed using imaging techniques when obstruction or another structural abnormality is suspected.

Transrectal ultrasonography and magnetic resonance imaging can provide information about the prostate, seminal glands, ejaculatory ducts, and nearby cystic or obstructive lesions.

Transrectal Ultrasonography

Transrectal ultrasonography provides close imaging access to the prostate and seminal tract through the rectum.

It can demonstrate abnormalities such as ductal dilatation, seminal gland changes, calcifications, or cystic lesions in appropriately selected patients.

Endoscopic Relationship

The openings of the ejaculatory ducts are anatomically accessible from the prostatic urethra.

Endoscopic visualization of the seminal colliculus provides orientation to the region where the ducts enter the urethra.

Seminal Colliculus as a Landmark

The seminal colliculus is an important urethroscopic landmark because it identifies the region of the prostatic utricle and paired ejaculatory duct openings.

Recognition of these relationships is important during procedures involving the prostatic urethra.

Clinical Importance

The ejaculatory ducts form a short but essential connection between the paired sperm-conducting ducts and the prostatic urethra. Their formation by the union of the ductus deferens and seminal gland duct means that obstruction can interfere simultaneously with delivery of sperm and seminal gland secretion.

Their intraprostatic location is particularly important clinically. Structural abnormalities within or adjacent to the prostate, including congenital cysts, inflammatory changes, calculi, and scarring, may compromise ductal patency. Because sperm production can remain normal in distal obstruction, disorders of the ejaculatory ducts must be distinguished from abnormalities of spermatogenesis.

Understanding the ejaculatory ducts also provides an important anatomical bridge between the testes, epididymides, ductus deferentes, seminal glands, prostate, and urethra. Their anatomy is therefore relevant to the study of male pelvic anatomy, ejaculation, semen transport, obstructive azoospermia, male infertility, prostatic anatomy, and reproductive tract imaging.

Key Anatomical Relationships

• The ejaculatory ducts are paired structures.
• Each is formed by the union of a ductus deferens with the duct of the corresponding seminal gland.
• They are approximately 2 cm long.
• They pass through the prostate.
• They terminate in the prostatic urethra.
• Their openings are associated with the seminal colliculus.
• The prostatic utricle opens between the paired ejaculatory duct openings.
• They carry sperm and seminal gland secretions.
• Prostatic ducts open separately into the prostatic urethra.
• The ejaculatory ducts develop in association with the mesonephric duct system.
• Sympathetic activity contributes to movement of reproductive fluids during emission.
• Bilateral obstruction can interfere with sperm delivery despite preserved testicular sperm production.