Reproductive System Of Bull

 Anatomy of the Male Reproductive Tracts

• Less complex than the females.

• Goal is to produce large numbers of viable male sex cells called spermatozoa.

• Contributes 1⁄2 of the chromosomes to each of his offspring

• After mating the role of the male is over

• Reproductive organs in the various mammalian species are similar in form and function.

Scrotum

The scrotum is a two-lobed sac that contains and protects the two testicles. It also regulates the temperature of the testicles, maintaining them at a temperature lower than body

temperature. When the environment temperature is low, the scrotum contracts. When the

environmental temperature is high, the scrotum relaxes. Maintaining the correct temperature

is critical in that being too hot or too cold can affect the production and vitality of sperm.

• Protects testes and Functions as a heat-regulating mechanism.

• 4 or 5 degrees below body temp. is essential for spermatogenesis – growth, and

maturation of the sperm.

Testes or testicles:

• Site of sperm production and testosterone synthesis

• Sperm contain 1⁄2 of genetic makeup

In the male testes are the primary sex organs and are held in a sac called the scrotum.

There are two testicles present in male mammals. Each testis is comprised of long, coiling

structures called Seminiferous Tubules. Each seminiferous tubule is comprised of connected

Sertoli cells and Leydig cells.

Sertoli cells have a “tight junction” barrier which serves to prevent the body from

destroying the sperm. The blood testes barrier is a physical barrier between the testes and the

seminiferous tubules.

Leydig cells/interstitial cells are dispersed throughout the testes and produce male

hormones (androgens) Testosterone is considered the primary male hormone. Testosterone is

released under the influence of LH from the pituitary gland, testosterone causes the

appearance and behavior of the animal to be masculine. Both LH and FSH are needed for

sperm production.

Epididymis - Sperm collection, storage, and maturation

The epididymis is the storage site for sperm cells. These cells enter the epididymis

from the testicle to mature. Sperm become able to fertilize a female’s ova or female sex cell,

in the epididymis. There is a separate epididymis attached to each testicle.

Vas deferens - The vas deferens is essentially a transportation tube that carries the sperm-

containing fluid from each epididymis to the urethra.

The urethra is a large, muscular canal or tube inside of the penis. Begins at the opening of

the bladder and is continuous with the penis. Both semen and urine move through the urethra

to the end of the penis. Urethra surrounded by a smooth muscle – crucial for ejaculation.

• In mature bulls, the posterior portion of the urethra is S-shaped – known as the

sigmoid flexure

• Extends the penis outside of the body and into the vaginal cavity of the female so that

the semen can be deposited.

The sigmoid flexure (found in bulls, rams, and boars) and the retractor muscle extend the

penis from the sheath, a tubular fold of skin. Horses and other mammals do not have a

sigmoid flexure.

“Accessory Sex Glands” along the urethra include the:

– Prostate Gland

– Two seminal vesicles

– Two Cowper’s

The accessory Sex Glands provide a medium for the transport of the sperm from the

testes to the vagina. These add volume and nutrition to the sperm-rich fluid coming from the

epididymis.

The Medium includes:

– Adds Volume

– Provides Nutrients for the sperm

– Cleans and flushes out the urinary tract.

– Makes a plug to hold the semen in the vagina (in some species)

Seminal vesicles— The seminal vesicles open into the urethra. They produce a fluid that

protects and transports the sperm. It secrete a fluid high in sugars (fructose) to nourish the

spermatozoa – feels like a bag of grapes (palpation). This fluid also dilutes sperm at

ejaculation and serves to activate motility – the bulk of fluid production occurs here. That is

Rich in proteins, fructose, enzymes. Secretes prostaglandins, causing uterine contractions.

Prostate gland— The prostate gland is near the urethra and the bladder. It produces a fluid

that is mixed with the seminal fluid. Creates a basic pH of 7.5-8 – protects sperm.

Cowper’s gland— The Cowper's gland produces a fluid that moves down the urethra ahead

of the seminal fluid. This fluid cleans, neutralizes, and helps protect the sperm through the

urethra. Lubricating & cleansing substance. Cleanse male and female reproductive tracts

prior to the passage of spermatozoa.

The mixture of the seminal and prostate fluid and the sperm is called semen.

Penis - an organ of copulation, places sperm in females.

The penis deposits the semen within the female reproductive system. The urethra in

the penis is surrounded by spongy tissue that fills with blood when the male is sexually

aroused. This causes an erection, enlarging it and enabling it to be inserted into a female’s

vagina that is necessary for copulation or mating to occur.

 Sperm moves by using their tails in a whip-like action – motile.

Sheath - the opening of the reproductive tract.