1. Male Reproductive System

2. I Can describe the structure and function of the male reproductive system including the following:
Testes
Seminiferous tubules
Interstitial cells
Epididymis
Vas deferens,
Cowper`s gland
Seminal vessicles
Prostate gland
Ejaculatory duct
Urethra
Penis

4. Review of Sexual Reproduction
Both parents donate genetic material
Offspring will be different than parents and each other
More variation in sexual reproduction than asexual
A parent cell divides to create two cells that are identical to one another and parent

5. Male Anatomy
Male and female sex organs originate in the abdominal cavity
During the third month the genes of the sex chromosomes cause differentiation
Testes descend through a canal in the scrotum

6. Urinary Bladder Temporary storage site for urine
Sphincter regulates the voiding of fluid from the bladder

7. Ureter
Carries urine from the kidneys to the urinary bladder

8. Scrotum Pouch of skin below the pelvis that contains the testes
Keeps testicles cool to allow production of sperm
Descend through small canal from abdominal cavity to scrotum during the last two months in utero
Membrane of skin forms over canal preventing testes from re-entering abdominal cavity

9. Scrotal Abnormalities
Deformities:
Undescended testicles
Testes fail to drop from body cavity
Abdominal cavity too warm to produce viable sperm; man is sterile
Inguinal hernia
Membrane separating abdominal cavity from scrotum gets ruptured, intestine can be forced into scrotum
Blood flow of testes and small intestine in danger due to pressure

10. y

11. u

12. Scrotal Abnormalities
Ruptured Testicle
Forceful, direct blow
50% from sports related injuries
If treated within 72 hours, 80% chance of salvaging damaged testicle

13. Testes Male gonads Produce sex hormones
Produce sex cells (sperm) in coiled seminiferous tubules
**use paint to white out labels....replace with new labels

14. Seminiferous Tubules Housed in the testes, which are about 5 cm long.
If uncoiled, they would measure 250m
Lined with sperm- producing cells called spermatogonia
Site of spermatogenesis, or the formation of sperm cells

15. Epididymus
Tightly coiled tube connecting the seminiferous tubules to the ductus deferens where sperm are mature and become motile

16. Vas Deferens Tube that conducts sperm towards the urethra
Carries sperm from the testis to the ejaculatory duct

17. Ductus Deferens
A storage duct that carries sperm and fluids (semen)from the epididymis to the ejaculatory duct

18. Ejaculatory Duct
A tubule formed where the vas deferens and seminal vessicle ducts meet, opens into urethra
Stores the sperm from vas deferens until needed
Propels the movement of semen into the urethra

19. Urethra
A duct, shared by the urinary and reproductive systems, that carries fluid through the penis
At any time, urethra conducts either urine or semen, but never both

20. Penis
Used to transfer sperm from the male to the female reproductive tract
Glans Penis
The enlarged tip of the penis

21. Foreskin
A flap of skin that protects the surrounds and protects the glans penis
The tissue that is removed during circumcision

22. Semen Secretion consisting of sperm and fluids
~1 tsp produced during ejaculation which contains roughly million sperm
2-3% sperm, remaining is seminal fluid

23. Vasectomy Common procedure to prevent pregnancy
Vas deferens from each testicle is cut and tied
Performed at Dr’s office with a local anaesthetic

24. Success Rates of Birth Control
Method
Used By
Type
Dr Rx?
Actual Failure Rate
Reversible
Abstinence
Both M & F
Natural No
0.0%
Yes
Condom
Male
Barrier
1-33%
Hormone Implant
Female
Hormonal
0.2%
No method -
>85% --
Oral
0.16-3%
Vasectomy
Surgical %
Possibly
Withdrawal
19%
Adapted from Adapted from: 1. Trussell J, Hatcher RA, Cates W, Stewart FH, Kost K. A Guide to Interpreting Contraceptive Efficacy Studies. Obstetrics and Gynecology 1990; 76: Mishell DR, Jr. Contraception. New England Journal of Medicine 1989; 320:

25. The Glands Seminal vessicle Prostate gland Cowper`s gland
Responsible for nourishing and lubricating sperm
Part of the endocrine system

26. Seminal vesicles
Produces a mucous-like fluid containing fructose (sugar) which provides energy for sperm

27. Prostate gland
Produces mucus-like alkaline fluid that neutralizes the acids from urine in the urethra

28. Cowper’s gland
Secretes alkaline mucus-like fluids into the urethra

29. Can you...? Identify the following structures on the diagram
Cowper`s gland
Prostate gland
Vas deferens
Ejaculatory duct
Urethra
Seminal vessicles
Seminiferous tubule
Epididymus
Testicles
Scrotum
Penis
Glans penis

31. ureter urinary bladder ductus deferens seminal vesicle urethra
prostate gland
Cowper’s gland
urinary bladder
ductus deferens
urethra
ductus deferens
seminal vesicle
urethra
ejaculatory duct
prostate gland
penis
Cowper’s gland
glans
penis
epididymis
foreskin
testis
scrotum

32. So what is the path that sperm travel???

33. Erection of the Penis

34. Sexual arousal:
Parasympathetic nerve causes arteries leading to the penis to dilate, increasing blood flow
Spongy tissue of the penis swells, squeezing veins that carry blood away from the penis
Penis engorges with blood and becomes erect

35. Spermatogenesis
1. Spermatogonia (sperm producing cells) divide to form spermacytes
2. Spermacytes differentiate into spermatids
Spermatids
Immature sperm cells
Contain only 23 chromosomes (half as much as other cells)
9-10 weeks to differentiate into sperm cell

36. Spermatogenesis
3. Sertoli cells found in the seminiferous tubules nourish the developing sperm cells to maturity
Sertoli cells
Provide a barrier between blood and testes
Barrier controls the entry/exit of hormones, nutrients; protecting the sperm cells
If barrier is damaged, body develops antibodies against its own sperm

37. Spermatogenesis
Sperm mature in the epididymis; defective sperm are destroyed here by the immune system

38. Sperm Swimming motion begins after 4 days in the epididymis
Streamlined design (reduced cytoplasm) for motion
Limited cytoplasm also means limited energy supply
Mitochondria found between the nucleus and the flagellum (propulsion)
Acrosome-cap on head of sperm cell, filled with enzymes that dissolve the outer coating of the egg

39. Seminal Fluid
Ejaculation is the process where semen leaves a man body through the penis
Sperm is forced to the base of the penis by the contraction of the vas deferens, seminal vesicles, ejaculatory duct and prostate gland
Strong muscular contractions force the semen into the urethra and out the penis

40. Seminal Fluid Seminal vesicles Prostate gland Cowpers gland
Release fluid containing fructose and prostaglandins
Fructose-energy supply
Prostaglandins-stimulate rhythmic contractions of smooth muscle along the female reproductive tract
Prostate gland
Secretes an alkaline buffer that protects sperm from acidic environment of vagina
Cowpers gland
Secretes mucus-rich fluid prior to ejaculation
Protects sperm from acids in the urethra
May help with sperm motility

41. Affect of Hormones on Male System
Primary sexual characteristics
Physical characteristics of an organism that are directly involved in reproduction
Present at birth
Secondary sexual characteristics
External features other than reproductive organs, that indicate gender

42. Testosterone
Primary male sex hormone produced in interstitial cells of testes
Triggers maturation of tests and penis, as well as spermatogenesis
Promotes secondary characteristics
Facial and body hair
Growth of larynx (deepening voice)
Strengthening of muscles
Sex drive

43. Hypothalamus and pituitary control production of sperm and sex hormones
Pituitary- produces and stores gonadotropic hormones (gonadotropins) which regulate the testes
2 gonadotropins
Follicle-stimulating hormone (FSH)
Turns on production of sperm cells in seminiferous tubules
Luteinizing hormone (LH)
Promotes production of testosterone by interstitial cells

44. Male Reproductive Hormones
Location
Function
Pituitary gland
Triggers production of sperm cells in seminiferous tubules
Interstitial cells
Luteinizing hormone
Stimulates secretion of FSH and LH
1. Follice Stimulating Hormone 2. Testosterone 3. Spermatogenesis, secondary sex traits, sex drive 4. Pituitary 5. Production of testosterone in interstitial cells 6. GnRH 7. Hypothlamus

45. Male Reproductive Hormones
Location
Function
Follicle Stimulating Hormone
Pituitary gland
Triggers production of sperm cells in seminiferous tubules
Testosterone
Interstitial cells
Spermatogenesis, secondary sex traits, sex drive
Luteinizing hormone
Pituitary
Production of testosterone in interstitial cells
GnRH
Hypothlamus
Stimulates secretion of FSH and LH
1. Follice Stimulating Hormone 2. Testosterone 3. Spermatogenesis, secondary sex traits, sex drive 4. Pituitary 5. Production of testosterone in interstitial cells 6. GnRH 7. Hypothlamus

46. When testosterone is low:
Negative feedback systems ensure that sperm cells and testosterone are maintained at constant levels
When testosterone is low:
Hypothalamus secretes GnRH
GnRH activates pituitary gland to release FSH and LH
FSH acts on sperm-producing cells in seminiferous tubules
LH stimulates testosterone production
Testosterone stimulates spermatogenesis
Negative feedback regulates LH and testosterone
High testosterone reduces LH production directly by feedback inhibition of LH release from the pituitary and indirectly from GnRH release from the hypothalamus
When hypothalamus detects high testosterone, releases less GnRH, which leads to less LH
Decreased GnRH slows down LH, which means lower testosterone

47. Production of testosterone
Spermatogenesis
STIMULATES
ACTS ON
Seminiferous tubules
ACTS ON
FSH LH
Hypothalamus
SECRETES
SECRETES
SECRETES
GnRH
ACTIVATES
Pituitary gland