Male Reproductive Anatomy & Physiology

Question 1

For a male mammal to reproduce, they must?
(4 points)

Answer 1

• Reach sexual maturity
• Produce viable sperm in sufficient quantity
• Accomplish mating successfully
• Provide parental care (in some species)

Question 2

Name the 4 main general features of the male reproductive system

Answer 2

• Gonads (testes) for gamete (spermatozoa)
• Tubes to carry sperm (vas deferens)
• Accessory glands to provide semen, nutrients & protection for sperm
• Penis ( & baculum in somespecies) for copulation

Question 3

What are the 2 functions of the testes?

Answer 3

• Produce gametes (sperm through spermatogenesis
• Secrete hormones (testosterone)

Question 4

What does the spermatic cord contain?

Answer 4

• Vas deferens
• Blood vessels
• Nerves supplying testes

Question 5

What is the structure of the testes?

Answer 5

• Septa divide testes into 250 - 300 lobules
• Each lobule contains 1-3 coiled seminiferous tubules with surrounding connective tissue

Question 6

What is the function of Sertoli cells?
Where are they located?

Answer 6

• Stimulate cells that form the sperm
• Produce androgen binding protein
• Produce hormones - inhibin & oestadiol
• Located within tubules

Question 7

What do Sertoli cells produce?

Answer 7

• Androgen binding protein – concentrates
testosterone & dihydrotestosterone (DHT)
that stimulate spermatogenesis
• Inhibin – inhibits FSH production
• Oestradiol – negative feedback on
hypothalamic GnRH production

Question 8

What are Leydig cells & where are they located?

Answer 8

• Interstitial cells
• Secrete testosterone in presence of LH
• Located in tissue between tubules

Question 9

What is the epididymis?

Answer 9

Highly convoluted duct on outer surface of testes

Question 10

Where do sperm mature & where are they stored?

Answer 10

Epididymis & vas deferens

Question 11

What is the vas deferens?

Answer 11

• Pained ducts that connect epididymis to urethra
• Also connects to a short duct within seminal vesicle (forms ejaculatory ducts)

Question 12

What is the urethra used for?

Answer 12

• Sperm & seminal fluid
• Urine

Question 13

What 3 chambers of tissue can be found in the body of the penis?

Answer 13

• Pair of corpora cavernosa on dorsal side
• Corpus spongiosum on ventral side

Question 14

What does urethra pass through?

Answer 14

The corpus spongiosum to its opening (the meatus) at the tip of the glans penis

Question 15

What is an erection controlled by?

Answer 15

A reflex arc that is mediated in the sacral spinal cord

Question 16

What does nitric oxide & cGMP do?

Answer 16

• Nitric oxide - dilates arteries
• cGMP - causes relaxation of smooth muscle in corpus cavernosum
• Results in high blood flow into penis

Question 17

What is a baculum?

Answer 17

• Penis bone
• Helps maintain stiffness during intercourse

Question 18

What are seminal vesicles?

Answer 18

Paired glands of base of vas deferens

produce about 60% of the total seminal fluid

Question 19

What is the function of seminal fluid?

Answer 19

Acts as a lubricant, pH buffer, & contains nutrients

Question 20

What nutrients does the seminal fluid contain?

Answer 20

• Fructose (energy source)
• Vitamin C
• Prostaglandins (stimulate muscular contraction)

Question 21

What is semenogelin?

Answer 21

A protein involved in formation of gel matrix that encases ejaculated sperm, preventing capacitation

Question 22

What is the function of the prostate gland?
(4 points)

Answer 22

• Produces 30 % of semen
• Helps neutralise acidity of vaginal tract to aid sperm motility
• Produces clotting enzymes to keep sperm in f reproductive tract
• Produces prostate - specific antigens to break down semen ‘clot’ to release sperm

Question 23

What does the bulbourethral gland produce?

Answer 23

• Drops of seminal fluid as pre-ejaculate
• Lubricates urethra for sperm

Question 24

What are ampullary glands?

Answer 24

Small glands located where vas deferens opens into urethra

Question 25

What is the purpose of the scrotum?

Answer 25

• Keeps testes ~2°C lower than body temp (35C)
• Sperm development is impaired at higher/lower temps

Question 26

What muscles contract when it is cold and relax when it is warm?

Answer 26

• Cremaster muscle
• Dartos muscle
• Draws testes closer to body to provide warmth

Question 27

Give 2 examples of animals that have internal testes

Answer 27

• Elephants
• Rhinos

Question 28

What are intestinal testes also referred to?

Answer 28

Abdominal testes

Question 29

Why do marine mammals not have external testes?

Answer 29

Would affect streamlined shapes & create drag

Question 30

What type of testes do marine mammals have?

Answer 30

• Internal
• Use an elaborate vascular countercurrent heat exchanger to keep temp below body temp for optimum function

Question 31

What are the several hypotheses for internal testes?

Answer 31

• Early primitive mammals had lower temperatures & their testes worked efficiently within their body
• Ancestor of eutherian mammals was a small mammal that required large testes form sperm competition (had to be placed outside body)
• Enzymes in spermatogenesis evolved an optimum temp slightly less than core temp, when animals became larger, they were stuck with enzymes that operated best at cooler temps
• Protects testes from abdominal cavity pressure changes caused by jumping/galloping

Question 32

What is sperm competition?

Answer 32

Where more than 1 m mates with a f, sperm from 2 or more males must compete to fertilise ova within a f reproductive tract

Question 33

What is the term for undescended testes?

Answer 33

Cryptorchidism

Question 34

What is cryptorchidism?

Answer 34

Undescended testes

Question 35

How is cryptorchidism resolved?

Answer 35

• Often by itself
• If not, an orchidopexy is performed before 1y/o

Question 36

What causes testicular torsion?

Answer 36

Twisting of spermatic cord (usually affects 1 testis)

Question 37

What is phimosis?

Answer 37

The opening of the tip of the foreskin is too narrow, so it cannot be retracted over head of penis

Question 38

What are the issues with phimosis + how can it be resolved?

Answer 38

• Weak urinary flow & painful erection
• Circumcision

Question 39

What is hypospadias?

Answer 39

• A congenital condition
• Opening of urethra is on underside of penis
• Corrected by surgery

Question 40

What can erectile dysfunction be treated with?

Answer 40

Sildenafil (Viagra)

Question 41

How does viagra work?

Answer 41

• By inhibiting phosphodiesterase 5
• In turn, inhibits hydrolysis of cGMP to GMP
• Enhances effect of NO
• Penile vasodilation is sustained

Question 42

Where in the testes are the sperm produced?

Answer 42

Epithelial lining of seminiferous tubules

Question 43

Why do marsupials have a bifurcated penis?

Answer 43

Female’s vagina has 2 lateral branches of vagina leading to 2 separate uteri

Question 44

List the main 3 male accessory glands

Answer 44

• Prostate gland
• Seminal vesicles
• Bulbourethral gland

Question 45

What is the main role of semen?

Answer 45

Provides protective, buffering medium for spermatoazoa

Question 46

What is the role of prostaglandins in semen?

Answer 46

Stimulate contractions of female uterus + aid sperm movement

Question 47

What is semenogelin & what does it do?

Answer 47

Protein involved in formation of a gel matrix that encases ejaculated sperm, preventing capacity ion