1. The Reproductive System
Ms. Marcos – Biology12

2. Sexual & asexual reproduction
offspring all have same genes (clones)
no variation
Sexual
gametes (sperm & egg)  fertilization
mixing of genes  variation

3. Mitosis vs Meiosis (A quick review!)
One diploid cell to one diploid cell
Identical copy
Meiosis
One diploid cell to 4 haploid cells
Half amount of DNA in new cells
Each unique
Crossing over makes new combinations of genes

4. The Male Reproductive System - Structures
Urinary bladder
Seminal vesicle (behind bladder)
Prostate gland
Bulbourethral (Cowper’s) gland
Urethra
Body of penis (erectile tissue)
Scrotum
Vas deferens
Epididymis
Testis
Glans of penis

5. The life of a male… (step-by-step)
Third month of development – male sexual structures develop
Last 2 months as a fetus – testes descend into the scrotum

6. Puberty and Spermatogenesis
Testosterone production increases
Secondary male characteristics
Spermatogenesis! (making sperm)
Testes filled with seminiferous tubules (250m in length!)
Spermatagonia = sperm producing cells
Undergo meiosis and create 4 spermatocytes
Differentiate into sperm cells (9-10 weeks)
Move to epididymus to mature
Develop flagella and swim (4 days)
Defectives destroyed by immune system
seminiferous tubule
sperm
spermatocytes

7. Spermatogenesis Epididymus Developing Spermatocytes Testis 1 diploid
spermatogonium
Sertoli cell
Meiosis I
Primary
Spermatocyte
Meiosis II
Seminiferous tubules
Secondary
Spermatocyte
4 haploid sperm
Inside a seminiferous tubule
Mature sperm

8. Spermatogenesis Sertoli cells
Nourish the developing sperm
Interstitial cells (between seminiferous tubules)
Produce testosterone

9. The Sperm Head Middle piece: Many mitochondria for energy
Neck
Midpiece
Head
Plasma Membrane
Tail (Flagellum)
Mitochondria
Nucleus
(haploid)
Acrosome
Head
Haploid nucleus
Acrosome  Enzymes used to enter the egg
Middle piece: Many mitochondria for energy
Tail: Flagellum for movement

10. Puberty continued: Ejaculation
First… a review of the parts involved:
Urinary bladder
Seminal vesicle
Rectum
Pubic bone
Ejaculatory duct
Body of penis
(Erectile tissue)
Vas deferens
Prostate gland
Urethra
Vas deferens
Bulbourethral (Cowper’s) gland
Glans of penis
Epididymis
Testis
Scrotum
Prepuce
(foreskin)

11. Ejaculation Vas deferens Parasympathetic nervous system
Carries the sperm from epididymus to urethra
Ejaculatory duct controls movement of sperm, sphincter regulates movement into urethra
Parasympathetic nervous system
Rush of blood to the penis
Sinuses swell, compressing the vein and trapping the blood
Seminal vesicles
Fructose = energy for the sperm
Prostaglindins = cause gentle contractions of the uterus

12. Ejaculation Prostate gland Cowper’s gland (bulbourethral gland)
Alkaline buffer protecting sperm against the acidic vagina
Cowper’s gland (bulbourethral gland)
Mucus-rich fluids aid movement and protect against acids in the male’s urethra
Urethra
Carries sperm out of the body through the penis
End result:
3-4 mL of fluid and about 500 million sperm!

13. Sex hormone control in males
GnRH = Gonatotropin Releasing hormone
FSH = Follicle Stimulating hormone
LH = lutenizing hormones (also called ICSH = Interstitial Cell Stimulating hormone)
Testosterone
Causes male secondary characterisitics
Aids in spermatogenesis (making sperm)
Hypothalamus
GnRH
Pituitary
FSH & LH
Testes
testosterone
Testes and Body cells

14. Negative Feedback controls spermatogenesis and testosterone production
Hypothalamus
GnRH
Anterior
Pituitary
FSH LH
Testosterone
Testis
Spermatogenesis

15. Questions… Other Questions?
Why do males need to produce so many sperm?
What is a vasectomy and why does it prevent males from getting a female pregnant?
What structures are inflamed if a male has epididymitius?
What could cause impotency (physically)?
What would a lack of testosterone do in a male?
Other Questions?