1. THE MALE REPRODUCTIVE SYSTEM

2. HOMEOSTASIS
male & female reproductive organs work together to produce offspring
female reproductive organs also contribute to sustaining the growth of embryos and fetuses

3. Sexual Reproduction
process by which organisms produce offspring by making germ cells (gametes)
fertilization: when male gamete (sperm) unites with female gamete (secondary oocyte)  fertilized egg
males & females have anatomically distinct reproductive organs that function to
produce gametes
facilitate fertilization
sustain growth of embryo & fetus (female)

4. Reproductive Organs Males Females Gonads: testes Ducts
store & transport gametes
Accessory Sex Glands
Supporting Structures
Penis
Gonads: ovaries
Ducts
transport gametes
Accessory Sex Glands
Supporting Structures:
Uterus

5. Male Reproductive System
Organs:
Testes
system of ducts
accessory sex glands
supporting structures:
scrotum
penis

6. Functions of the Male Reproductive System
Testes produces sperm & the male sex hormone Testosterone (T)
Ducts transport, store, & assist in maturation of sperm
Accessory sex glands secrete most of liquid portion of semen
Penis contains the urethra, passageway for ejaculation of semen & excretion of urine
Scrotum protects temperature-sensitive testes from temperature fluctuations

7. Scrotum a supporting structure for the testes features:
loose skin & superficial fascia attached from root of penis
externally:
raphe: median ridge that separates scrotum into right & left sides
internally:
scrotal septum: divides scrotum into 2 sacs, each with 1 testes

8. Scrotum - 2 features continued: dartos muscle: smooth muscle fibers
contraction causes wrinkled appearance (reduces heat loss)
cremaster muscle: skeletal muscle
2 features regulate temp of testes:
location outside trunk keeps temp 2 – 3 °C lower than core body temp
in response to cold temps, both muscles contract moving testes closer to body so can absorb body heat

10. Testes (plural)/ Testis (singular)
aka testicles
paired oval glands develop near kidneys  begin descent into scrotum thru inguinal canals during latter half 7th month gestational age
leading edge covered with peritoneum called tunica vaginalis
Hydrocele: serous fluid collects between this & testis (injury or inflammation of epididymis)

11. Hydrocele

12. Testes - 2 tunica albuginea: internal to tunica vaginalis
dense irregular CT
extends inward into testis forming septa: divide testis into series of 200 – 300 lobules (internal compartments)
each lobule contains 1 – 3 coiled seminiferous tubules : *site of production of semen
spermatogenesis: process by which seminiferous tubules produce sperm

13. Testes

14. Seminiferous Tubules 2 types of cells: spermatogenic cells
sperm-forming cells:
spermatogonia: stem cells  primordial germ cells
arise in yolk sac & enter testes during 5th wk of development: remain dormant until puberty
1° spermatocytes, 2° spermatocytes, spermatids, sperm cells (layers of progressively more mature cells)
Sertoli cells
function in supporting spermatogenesis

16. Spermatogenesis

17. Sertoli Cells aka sustentacular cells
extend from basement membrane  lumen of tubule
held together by tight junctions
form obstruction known as the blood-testis barrier: all substances must pass thru Sertoli cells to reach developing sperm cells (after spermatogonia)

18. Sertoli Cell

20. Functions of the Sertoli Cells
nourish spermatocytes, spermatids, & sperm
phagocytoze excess spermatid cytoplasm as they develop into sperm
control movements of spermatogenic cells & release of sperm into lumen of seminiferous tubules
produce fluid for sperm transport
secrete hormone inhibin
mediate effects of T & FSH

21. Leydig Cells interstitial cells (between seminiferous tubules)
*secrete T

22. Sperm ~300 million sperm complete spermatogenesis/d ~60 μm long
once ejaculated last ~48 hours w/in female reproductive tract

25. Hormonal Control of the Testes

26. Ducts of the Male Reproductive System
fluid secreted by Sertoli cells generates pressure which pushes sperm & fluid along lumen of seminiferous tubule  eventually released as ejaculate

27. Epididymis epi = over or above / didymis = testis
aka: ductus epididymis
plural:epididymides
comma-shaped organ
lies along posterior border of each testis
ductus epididymis
head
body
tail

29. Ductus Epididymis ~6 m in length
pseudostratified columnar epithelium lined with microvilli called stereocilia
increase surface area for reabsorbing degenerated sperm
surrounded by smooth muscle
Function of epididymis:
*sperm maturation (acquire motility & ability to fertilize an ovum)
smooth muscle contraction propels sperm into ductus deferens
sperm storage (viable up to several months)

30. Ductus Deferens/ Vas Deferens
ascends along posterior border of epididymis  inguinal canal entering pelvic cavity  loops over ureter  passes down posterior surface of urinary bladder
terminal end is dilated = ampulla
pseudostratified columnar epithelium
3 layers smooth muscle (inner & outer layers longitudinal, middle layer circular)

31. Function of Vas Deferens
conveys sperm from epididymis  urethra by peristaltic contractions
sperm storage (several months)
sperm not ejaculated are reabsorbed

33. Vasectomy main method for sterilization of males
portion of each vas deferens is cut out & ends ligated
sperm
production continues but do not reach exterior
degenerate & destroyed by phagocytes

34. Ejaculatory Ducts
formed by union of duct from seminal vesicle & ampulla of ductus deferens
pass inferiorly & anteriorly thru prostate gland
terminate in prostatic urethra where they eject sperm & seminal vesicle secretions just before the release of semen from urethra to exterior

36. Urethra shared terminal duct of reproductive & urinary systems
passes thru:
prostate
deep muscles of perineum
penis

37. Urethra 3 parts: Prostatic Urethra Membranous Urethra
portion thru deep perineal muscles
Spongy (penile) Urethra
portion thru corpus spongiosum of penis
ends at external urethral orifice

38. Parts of Male Urethra

39. Accessory Sex Glands secrete most of liquid portion of semen Include:
Seminal Vesicles
Prostate
Bulbourethral Glands

40. Seminal Vesicles aka seminal glands
paired, convoluted, pouchlike structures
posterior to base of urinary bladder (superior surface) & anterior to rectum
*secrete alkaline, viscous fluid: (~60% of vol of semen)
fructose
prostaglandins
clotting proteins (different from those in blood)

41. Seminal Vesicles Fluid
alkaline to neutralize acidic environment of male urethra & female vagina (acids inactivate or kill sperm)
fructose:used for ATP production in sperm
prostaglandins contribute to sperm motility & viability
clotting proteins help semen clot after ejaculation

42. Prostate single, donut-shaped gland ~size of a golf ball
inferior to urinary bladder
surrounds prostatic urethra
increases in size from birth to puberty when it expands rapidly until ~ age 30, remains stable ~ age 45, further enlargement may occur after that

44. Prostatic Fluid milky, slightly acidic ~25% of vol of semen
empties  urethra thru many prostatic ducts
contains:
citric acid (ATP production in sperm)
several proteolytic enzymes
PSA: prostate-specific-antigen
acid phosphatase (function unknown)
seminalplasmin: bacteriocidal

45. Bulbourethral Glands aka Cowper’s glands
pea sized, inferior to prostate gland on either side of membranous urethra
ducts open into spongy urethra
secrete
alkaline fluid (protects sperm from acidic environment of spongy urethra)
mucus  lubricates end of penis & lining of urethra (decreases # of sperm damaged during ejaculation)

47. Semen mixture of sperm & seminal fluid
(secretions of seminiferous tubules, seminal vesicles, prostate, & Cowper’s glands)
average vol: 2.5 – 5 mL with 50 – 150 million sperm/mL
<20 million sperm per mL probably infertile
pH: 7.2 – 7.7
provides sperm with:
transportation medium
nutrients
protection from hostile acidic environment of male urethra & female vagina

48. Penis contains urethra passageway for urine & semen Parts: Body
Glans Penis
Root

50. Body of the Penis Corpora Cavernosa: Corpus Spongiosum:
2 dorsolateral masses
Corpus Spongiosum:
midventral mass
spongy urethra w/in

51. Circumcision
portion of prepuce (fore skin)surgical excised 3 – 4 days after delivery or 8th day for Jewish rite