Seminal vesicle

The seminal vesicles are paired accessory sex glands of the male reproductive system. The seminal vesicle produces over two-thirds of the ejaculate and is very high in fructose. 

Gross anatomy

The seminal vesicle is actually a 10-15 cm long tubular structure but is coiled tightly so it only measures 4-5 cm in length. It is located superiorly and posteriorly to the prostate.

The excretory duct of the seminal vesicle unites with the ductus deferens to form the ejaculatory duct. 

Relations

• anteriorly: base of bladder
• inferiorly and anteriorly: prostate
• posteriorly: rectovesical fascia
• medially: ampulla of ductus deferens
• laterally: prostatic venous plexus
• superiorly: tips of the seminal vesicles covered by the peritoneum of the rectovesical pouch

Arterial supply

• artery to the ductus deferens from superior or inferior vesical arteries ^3,4

Venous drainage

• vesical venous plexus into internal iliac veins

Lymphatic drainage

• drain to internal iliac lymph nodes ⁹

Innervation

• sympathetic fibres from the testicular and hypogastric plexuses ⁴

Variant anatomy

• congenital absence of seminal vesicles ⁹

Radiographic features

Ultrasound

• fluid-filled structure located posteriorly and superiorly to the prostate gland ²

CT

• has a typical "bow-tie" appearance and soft-tissue density; located between the prostate and the bladder ^2,5
• normally separated from the bladder by a fat plane
• normally are less than 1.5 cm in diameter, beyond that they can be considered dilated ⁵

• according to one publication the mean length was estimated to be around 3 cm with the mean width at around 1.5 cm ⁶

• they may be larger in those with autosomal dominant polycystic kidney disease ⁷

MRI

• T1: low-to-intermediate signal
• T2: convoluted areas of high signal representing seminal fluid and low signal walls ⁵

Related pathology

• seminal vesicle cysts
• seminal vesicle abscess