Veterinary Andrology and Reproductive Techniques

ACCESSORY SEX GLANDS

(Vesicular glands or Seminal vesicles / Prostate gland / Bulbourethral or Cowper's gland)

Vesicular glands/seminal vesicles/glandulae vesicularis

• Paired glands having distinct lobulations
• Located on the pelvic floor cranial and lateral to the ampullae and neck of the bladder
• The lobes of the seminal vesicles have small central dilatation in ruminants and boar but large dilatation in horse.
• So the name vesicular gland is used in all species except in horse where it is called as seminal vesicle.
• Tubular secretary glands present in the vascular glands add volume, nutrition and buffers in the semen
• These glands open in the pelvic urethra near the opening of the ampullae (colliculus seminalis)
• It will not store spermatozoa
• The approximate dimensions of the vesicular glands in different species are as follows

Species	Length	Breadth	Thickness	Weight
Bull	10-15 cm	2-4 cm	2 cm	75 gm
Stallion	15-20 cm	2.5-5 cm	5 cm	--
Boar	12-15 cm	5-8 cm	4 cm	200 gm
Ram	4-5 cm	2 cm	1.5 cm	5 gm

• The secretions of seminal vesicles are rich in fructose and citric acid.
• They also have protein, potassium bicarbonate, ascorbic acid, acid soluble phosphate and enzymes.
• It’s secretion contribute about 50% of the total ejaculate of semen.
• Compared to prostatic secretions, the vesicular secretions are more alkaline.
• In boar the vesicular secretion has high inositol contents and also contains ergothioneine.
• In bulls the secretion of vesicular gland is yellow due to high riboflavin contents. These glands are absent in dog and cat.

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Prostate gland

• The prostate gland has different forms in different species.
• In bull, it is a single gland located on the pelvic floor, on or around the neck of the bladder or the cranial portion of the pelvic urethra.
• The gland opens into the pelvic urethra lateral to the “colliculus seminalis” (opening of the ampullae) through many ducts.
• In dog there are only two excretory ducts of prostate gland.
• In bull the prostrate gland surrounds the pelvic urethra and has two parts - pars propria (body of the prostate) and pars disseminata which surrounds the pelvic urethra.
• The approximate dimensions of the prostate gland in bull and boar are as follows:

Pars propria (cm)	Pars disseminata (cm)
Bull 3 x 1 x 1	12 x 1.5 x 1.0
Boar 3 x 3 x 1	17 x 1.0 x 1.0

• In ram, the prostate gland has no body and is diffused over the large portion of the pelvic urethra.
• In stallion, the prostate gland consists of two lateral lobes connected by isthmus
• In dogs it is the only accessory sex gland available.
• The size of the prostate gland varies greatly and may be quite large in older dogs. Some disseminate lobes are present in the urethral wall.
• Prostatic fluid is a source of male antagglutin and secretes fluids rich in mineral content.
• The secretions are rich in enzymes that resemble interior milieu of the cells rather than the external milicu of the cell e.g. glycolitic enzymes, proteinases, phosphatases, glycosidases, nucleases and nucleotidases.
• In dog the pH of the prostatic secretion is 6.5 and there are no reducing sugars. However, canine prostate secretion has high concentration of zinc.
• Zinc concentration in the seminal plasma is chiefly due to prostatic secretion.

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Bulbourethral gland (Cowper’s gland)

• In bull, the bulbourethral glands are the paired glands lying on either side of the pelvic urethra in the region near the ischial arch.
• In bull, these glands are embedded under the bulbospongiosus muscle. These gland are ovoid in bull, stallion and ram and are cylindrical in boar.
• In bulls it is slightly smaller than stallion. In rams it is relatively large and in boars it is larger.
• These glands are absent in dog. In cat these are of the size of the prostate.
• The dimensions of the bulbouretheral gland in different species of animals are as follows:

Species	Diameter (cm)	Length (cm)
Bull	1.5-3.0	-
Stallion	2.5-5.0	-
Ram	0.5-1.0	-
Boar	2.5-3.0	12.0

• In bull and boar each gland opens in urethra through a single duct, but in stallion each gland opens into the urethra through 6 to 8 secretary ducts.
• In bulls, the dribbling seen from the prepuce prior to mounting are secretions from the prostate and bulbourethral glands.
• These secretions clean the passage of semen prior to ejaculation.
• The typical rubber like white subsance is filled in the Cowper’s glands of the boar that is essential for gel formation in boar semen.
• Blood supply – Internal pudental artery (in all species except in dog where a branch of urogenital artery arising from internal iliac artery supplies)
• Nerve supply – Autonomic nerves from hypogastric nerves and pelvic plexus

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