Corpus: Vesicular gland

The vesicular gland is a paired accessory sex gland in males.

Since the vesicular gland does not contribute to the production or maturation of sperm, the older term "seminal vesicle" is considered misleading and is less commonly used in recent literature.

3.1. Morphology

The vesicular gland is an elongated oval structure, about 5 cm in length, with a knotted appearance. It consists of a highly folded glandular tube and can hold a volume of about 4 ml. Its excretory duct, joins with the deferent duct to form the ejaculatory duct, which opens into the urethra.

3.2. Embryology

The vesicular gland develops embryologically from the Wolffian duct.

3.3. Topography

The paired vesicular glands are located behind the fundus of the urinary bladder. They are positioned as follows:

• Ventrally: urinary bladder
• Dorsally: rectum
• Caudally: prostate
• Medially: ampulla of deferent ductus

The cranial and dorsal parts of the vesicular gland are sometimes covered by peritoneum, though most of the gland lies outside the peritoneal cavity.

3.4. Vascular supply

Arterial blood is provided by branches of the inferior vesical artery from the internal iliac artery, along with additional branches from the artery of the ductus deferens. Venous drainage occurs via the vesicoprostatic venous plexus, which drains into the vesical veins. Lymphatic drainage primarily goes to the internal lymph nodes, with a smaller portion reaching the presacral lymph nodes.

3.5. Innervation

The vesicular gland is primarily innervated by sympathetic fibers from the inferior hypogastric plexus, which facilitate smooth muscle contraction during ejaculation. Parasympathetic fibers from the same plexus also play a role, regulating secretion production.

The vesicular gland has a three-layered structure, consisting of the mucosa, muscularis, and adventitia.

The mucosa is lined with a one- to two-layered epithelium, which can be either highly prismatic or isoprismatic. The mucosa exhibits numerous folds and is supported by the lamina propria.

The muscularis is made up of smooth muscle cells, which are often difficult to distinguish from the lamina propria under the microscope. This layer contains fibroblasts and bundles of collagen fibers. Some muscle strands extend into the larger folds of the mucosa.

The adventitia is composed of loose connective tissue, containing nerves and blood vessels. It serves to anchor the vesicular gland to surrounding structures.^[1]

The vesicular gland produces an alkaline secretion, rich in fructose, which constitutes about 70 % of the ejaculate. This secretion provides energy for sperm motility, while its alkaline nature enhances sperm movement.

Additionally, the vesicular gland secretes semenogelin, a protein that encases sperm in a gel matrix, preventing premature capacitation. This protein is cleaved in the prostate by PSA (prostate-specific antigen), enabling the sperm to become fully motile.