What are the Accessory Glands of Male Animals? (Bull, Stallion, and Buck)

There are three accessory glands of the male animals that produce a bulk of the genital fluid. Here, I will identify these glands with their anatomical features from different male animals.

Quick answer: seminal, prostate, and bulbourethral are the accessory glands of male animals. Except for the prostate gland, the other two glands are paired and have considerable variation in shape and size among various species.

First, I will identify and describe the anatomy of the bull accessory glands. Then, I will differentiate these glands from other animals compared to the bull.

What are the accessory glands of male animals (bull)?

The accessory glands of male animals like bull includes the following –

  • Seminal vesicle or vesicular glands – paired lobulated glands,
  • Prostate gland – unpaired but has two sub lobes, and
  • Bulbourethral or Cowper’s glands – paired gland,

Again, the ampulla of the ductus or vas deferens is also included under the accessory genital glands of the bull. The ductus deferens are two in number in a bull and pass through the inguinal canal.

You may find the detailed guide on the ductus deferens of the bull from the bellow-mentioned article –

Here, the diagram identifies the three accessory genital glands from the bull reproductive system. The relative location of these three glands is similar in all animals.

Accessory Glands of the Bull
Accessory Glands of the Bull

You will only find the variation in the shape and size of the genital glands in various animals. Table 1 shows the variation of these glands in different animals like bull, stallion, buck, and boar –

Accessory glandsSeminal vesicleProstate glandCowper glandAmpulla
BullModerate size
Small body
Have disseminated lobes
Covered by urethralis muscle
Body has two undisseminated lobesPresentLarge
DogAbsentHave two distinct lobes
Absent Large
BuckModerate size
Have disseminated lobes onlyPresentSmall
BoarVery large size
Small body
Have disseminated lobes
Covered by urethralis muscle
Very large Small
Accessory Genital Glands in Animals (Bull, Stallion, Buck, and Boar)

Now, let’s know the details of the anatomy of these three accessory glands of a bull with a diagram.

Vesicular glands or seminal vesicles of a bull

These are the two elongated and lobulated accessory glands in the bull. They are unsymmetrical in shape and have thick walls.

If you dissect the seminal vesicle of a bull, you will find the sacculated and tortuous tubes.

Location: the bull’s seminal vesicles lie on each side of the caudal part of the dorsal surface of the urinary bladder. So, the glands are related to the last part of the large intestine dorsally.

The seminal vesicles of the bull possess 2 surfaces –

  • Dorsal surface – faces dorsally and medially. The peritoneum covers the dorsal surface of the bull’s seminal vesicles.
  • Again, the ventral surface of the vesicular glands faces ventrally and medially. But, you will not find any peritoneal covering on the ventral surface of the bull’s vesicular glands.

Excretory ducts of bull’s seminal vesicles: Each seminal vesicle possesses one excretory duct. The excretory ducts open at the seminal colliculus just lateral to the opening of corresponding vas deferences.

Species differences in the vesicular glands

Boar: The vesicular glands of the boar are comparatively larger and lobulated. The excretory ducts from the boar’s vesicular glands open into the urethra separately from the vas deferens.

Stallion: The vesicular glands of the stallion are hollow and pear-shaped sacs. They are also lobulated and located in a similar location to the bull.

Circulation and innervation of bull seminal vesicles: vesicular artery (branch of urogenital artery), and pelvic plexus.

Bull prostate gland anatomy

The bull prostate gland is unpaired and pale yellowish. However, it consists of two lateral lobes that are connected by an isthmus.

Location of the bull prostate gland: It lies between the neck of the urinary bladder and the origin of the urethra. This gland is dorsally related to the last part of the bull’s large intestine.

The two lobes of the bull prostate glands are – the right and left lateral lobes. Again, the connecting isthmus is a thin and transverse band.

Both the lateral lobes of the bull prostate gland are prismatic in shape. They are directed cranially, laterally, and somewhat dorsally.

Anatomically, this prostate gland exhibits 3 surfaces and a pointed apex. The surfaces of the bull’s prostate glands are –

  • Deep surface – concave and partly embraces corresponding seminal vesicle,
  • Dorsal surface – concave and covered with urethralis muscle, and
  • Ventral surface – convex and related to the urethra,

Why is the bull prostate gland often hard to identify grossly?

Answer: The bull prostate gland is concealed by the urethralis muscles and its aponeurosis. Thus, it often escapes notice grossly. But, this accessory gland of the bull is very evident on the cross-section.

Prostatic ducts of the bull prostate gland

There are multiple (typically four) prostatic ducts of the bull prostate gland that open on the urethra in rows.

Two of the prostatic ducts: open between two folds of mucous membrane that are processed caudally from seminal colliculus and

Other two of the prostatic ducts: open on either side lateral to the mucosal folds,

Summary of the opening of bull prostatic ducts: into the urethra on either side of mucous folds at the roof behind seminal colliculus.

Bulbourethral or Cowper’s glands in bull

The bulbourethral glands of the bull are paired and often escape notice grossly. They are covered by a thick layer of dense fibrous tissue and partly by bulbospongiosus muscle.

Location: the bull’s bulbourethral glands are located on either side of the pelvic part of the urethra. Thus, it remains just cranial to the ischial arch but caudal to other accessory genital glands.

Each bulbourethral gland comprises several tubules. These tubules have a single bulbourethral duct.

Now, these ducts of the bull’s bulbourethral gland open into the urethra on the dorsal wall. The folds of mucous membranes cover this dorsal wall.

Species difference of bulbourethral glands

Stallion: the bulbourethral glands are larger in stallions. However, it is hard to notice grossly due to the presence of folds of mucous over the glands.

Dog and boar: bulbourethral glands are absent from the dog’s genital system. However, the boar has larger and elongated bulbourethral glands. They are located on either side of the dorsolateral aspect of the caudal part of the boar’s pelvic urethra.

What are the ampullae in animals?

Answer: The ampullae are the glandular enlargements at the terminal part of the vas deferens. They are considered part of the accessory glands of the male animals.

These ampullae are well-developed in the stallion, bull, and buck. But, this ampulla is absent in the boar genital system.

The glands of the ampullae empty into the vas deferens and contribute volume to fluid.

What is the function of accessory reproductive glands in animals or cattle?

Answer: The accessory reproductive glands (seminal vesicle, prostate, and vesicular) in animals like cattle produce the bulk of genital fluid. Again, the ej fluid provides favorable conditions for the nutrition of the sperm.

It also acts as a buffer against the natural acidity of the female genital tract. The prostate produces an alkaline secretion that gives the ej-fluid its characteristic odors.

Again, the bulbourethral glands of the ampullae contribute to increasing the volume of ej-fluid.

What are the accessory glands of the stallion?

Answer: The stallion has the following accessory glands –

  • Seminal vesicles or vesicular glands -elongated and somewhat piriform sac-like structures,
  • Prostate gland – single gland but possess more distinct right and left lateral lobes,
  • Bulbourethral or Cowper’s glands – larger, oval, and depressed dorsoventrally and
  • Ampullae – have larger ampullae in the stallion that contain the glandular tissue,


So, this article provides a concise answer to the question – what are the accessory glands of male animals? Vesicular, prostate, and Cowper’s are the three major accessory glands of male animals like bulls and stallions.

The gross anatomical features of the accessory glands of male animals is almost similar, with few exceptions. You may now identify these glands from various animals’ genital systems at your anatomy learning laboratory.