Male Reproductive System

What do testicles (gonads) produce?

Male gametes (sperm) and male sex hormones (testosterone)

What do the two testicles descend through?

Inguinal canal

What is the failure of one testicle to descend called?

Monorchid

What is the failure of both testicles to descend called?

Cryptorchid

What do retained testicles still make? What do they not produce?

Still make testosterone

Do not produce sperm

(will still mate but infertile)

What is an intact adult male horse called?

Stallion

What is an intact adult male ox called?

Bull

What is an intact adult male pig called?

Boar

What is an intact adult male sheep called?

Ram

What is an intact adult male goat called?

Buck (billy)

What is an intact adult male chicken called?

Rooster

What is a castrated male horse called?

Gelding

What is a castrated male ox called?

Steer

What is a castrated male pig called?

Barrow

What is a castrated male sheep called?

Wether

What is a castrated male goat called?

Wether

What is a castrated male chicken called?

Capon

What are some differences in testes location?

Pendulous vs non-pendulous

Relation to sigmoid flexure (absent in stallion)

What does pendulous mean?

hanging down loosely

Do all males share the same basic tubes and physiology to produce and deliver spermatozoa?

Yes

What houses the testes and regulates temperature?

Scrotum

What must scrotum temperature be for spermatogenesis?

Below core body temperature

What is the smooth muscle under the scrotal skin that has sensory neurons that detect temperature?

Tunica dartos

How does the Tunica dartos muscle regulate temperature?

Contracts to pull testes closer (warmth)

Relaxes to cool

Can hold contractions for a long time (smooth muscle)

What is the spermatic cord also involved in?

Temperature regulation

What is along the spermatic cord attached to the testes that helps regulate temperature?

Cremaster muscle

What does contraction of the cremaster muscle aid?

Blood flow and cooling efficiency

What are the two blood supplies to the testes?

Pampiniform plexus

Convoluted testicular artery

How does the pampiniform plexus cool arterial blood?

Counter current heat exchange

What does the pampiniform plexus look like?

Single artery surrounded by network of veins (increases surface area)

Where is the convoluted testicular artery?

On the testes surface

In the ram, how much does blood temperature drop before entering the testes?

4 degrees Celsius

What does thermal regulation involve?

Scrotum

Testes

Spermatic cord

What is the functional unit and site of spermatogenesis?

Seminiferous tubules

What do the seminiferous tubes contain?

Sertoli cells (nurse cells)

What contains Leydig cells?

Interstitial space

What cells produce testosterone?

Leydig

What is the sperm pathway?

Seminiferous tubules to rete testis

Efferent ducts to epididymal duct

What concentrates, stores, and transports, sperm and houses sperm maturation?

Epididymis

What are the parts of the epididymis?

Head, body, tail

Where is the epididymis located?

Outside testes

How long does sperm maturation take?

Around 40 to 60 days depending on species

What connects the epididymis to the urethra and transports sperm at ejaculation?

Ductus (vas) deferens

What is cut during sterilization procedures?

Ductus (vas) deferens

How much of ejaculate volume do accessory sex glands secretions make up?

50-90%

What are the enlargements at the end of ductus deferens that add volume?

Ampullae

What species are ampullae developed in? Absent in?

Developed in stallion, bull, ram

Absent in boar

What supplies nutrients (carbs, buffers, enzymes for activation)?

Vesicular glands (seminal vesicles)

What species do the seminal vesicles contribute large volume in?

Stallion

Boar

What cleans and lubricates the urethra and secretes alkaline?

Prostate gland

What does the alkaline secretion of the prostate gland cause?

Characteristic semen odor

If the prostate gland is enlarged, what might happen?

May prevent urine flow

What happens if there is urine leftover?

High salt = ruptures sperm

What else cleans and lubricates the urethra and has a thick, viscous, slippery secretion?

Bulbourethral (Cowper's) gland

In the boar what does the Cowper's gland produce?

Gelatinous material, forming cervical plug

How much semen do rams produce in milliliters?

0.5-2.0

How much semen do bulls produce in milliliters?

3-10

How much semen do stallions produce in milliliters?

40-100

How much semen do boars produce in milliliters?

150-250

How much semen does man produce in milliliters?

2-6

What is the organ of copulation in males?

Penis

What does the urethra carry through the penis?

Sperm

Urine

What is the erectile tissue of the penis called?

corpora cavernosa

What kind of penis is firm when not erect?

Fibroelastic (ruminants, swine)

What kind of penis is flaccid when not erect?

Musculocavernous (stallion)

What penis muscle relaxes during sexual excitement?

Retractor

What does the bull glans penis look like?

Tapers

What does the ram glans penis look like?

Filiform appendage (spongy string deposits semen anterior vagina)

What does the boar glans penis look like?

Spiral motion deposits semen in cervix

What does the stallion glans penis look like?

Bloated end, presses against cervix (deposited in cervix)

Where does spermatogenesis (sperm production) occur?

Seminiferous tubules

What cells nourish sperm and contain androgen-binding protein?

Sertoli cells

What are the two phases of spermatogenesis?

Mitotic divisions (spermatocytogenesis) (diploid)

Meiotic divisions (reduce chromosome number to haploid)

What is the product of the first division?

Two diploid cells

What is the product of the second division?

Two haploid sperm cells (two with X chromosome and two with Y chromosome)

What is the function of the head of the sperm cell?

Genetic material and acrosomal enzymes

What is the function of the neck of the sperm cell?

Connects head to midpiece

What is the function of the midpiece of the sperm cell?

Energy production

What is the function of the tail of the sperm cell?

Movement

What does the sperm cell look like in horses?

More cylindrical

What does the sperm cell look like in man?

Head like inverted egg

What does the sperm cell look like in rats?

Bent/curved

What does the sperm cell look like in roosters?

Long, straight, slender

What does the hypothalamus (brain) produce?

GnRH (gonadotropin-releasing hormone)

What does GnRH trigger?

release of LH and FSH from anterior pituitary

What does LH stimulate?

leydig cells to produce testosterone

What does are the effects of testosterone?

Accessory gland development

Reproductive tract growth (puberty)

Initiates spermatogenesis

Supports sperm survival

What are the secondary sex characteristics caused by testosterone?

Deep voice

Muscle development

Neck crest

Libido

Whiskers in man

What does FSH stimulate?

Sertoli cells to produce sperm nutrients

What kind of response is erection?

Neural (parasympathetic)

What are some stimuli to erection?

Touch, sight, environment

Visual (female in estrus) or learned (stallion walking to breeding area)

What does erection require?

Vasodilation (increased blood flow)

What is before ejaculation called?

Emission

Where does the sperm move during emission?

Epididymis to vas deferens to pelvic urethra

What is sperm mixed with in the urethra?

Accessory gland secretions

Contractions eject semen