Seminal vesicles

The seminal vesicles are a pair of "tube-like" glands. They are found behind the bladder of males. They make about 70% of the content of semen (also called seminal fluid).

Seminal vesicle
Cross-section of the lower abdomen in a male, showing parts of the urinary tract and male reproductive system, with the seminal vesicles seen top right
The seminal vesicles seen near the prostate, viewed from in front and above.
Details
Precursor	Mesonephric ducts
System	Male reproductive system
Artery	Inferior vesical artery, middle rectal artery
Lymph	External iliac lymph nodes, internal iliac lymph nodes
Identifiers
Latin	vesiculae seminales, glandulae vesiculosae
MeSH	D012669
TA	A09.3.06.001
FMA	19386
Anatomical terminology [edit on Wikidata]

Anatomy

Both vesicles are about 5 cm in length, but they are curled up. Each gland makes a ball shape on the wall of each vas deferens. There is a tube linking the seminal glands which opens into the vas deferens and prostate gland.

From inside to out, the layers making the vesicles are:

• Mucosa - folded to increase surface area
• Muscle
• Connective tissue

Use

The seminal vesicles make most of semen, but during ejaculation, most of the ejaculate has sperm rather than semen in it. The use of seminal fluid is not known, since sperm do not move or survive well in semen. Some think that it acts as a fluid to stop sperm from another male impregnating the female so that the children of only one male can survive.

Seminal fluid has proteins, enzymes, fructose, mucus, vitamin C and flavins. The fructose gives sperm energy and 'food'.