Difference between Meiosis and MitosisDifference between Meiosis and Mitosis

Meiosis IMeiosis I

Interphase Prophase I Metaphase I Anaphase I Telephase I

Meiosis IIMeiosis II

Prophase II Metaphase II Anaphase II Telephase II

Male Reproductive

System

• Reproductive Anatomy of the Human Male.• External:

- penis - scrotum

• Internal: - gonads- accessory sex glands and ducts.

Human reproduction involves intricate anatomy and complex behavior

Male Reproductive System

Testes

Male Reproductive System

Male Reproductive System

External structure of the penis:

• glans penis

• prepuce (foreskin)

• There is no verifiable health benefit to circumcision.

Circumcision

foreskin glans penis urethral opening

suturesshaft

corona

• The penis is composed of three layers of spongy erectile tissue.• During sexual arousal the erectile tissue fills

with blood from arteries.• The resultant increased pressure seals off the

veins that drain the penis.

•The engorgement of the penis with blood causes an erection.

• Testes are the male gonads.• seminiferous tubules- form sperm • Leydig cells (interstitial cells)- produce

androgens (ex. Testosterone, ABP).

•Testes are located in the scrotum, outside the body cavity.• This keeps testicular temperature cooler

than the body cavity.

• The testes develop in the body cavity and descend into the scrotum just before birth.

•Sperm Pathway

Prostatic urethra

Membranous urethra

Semen

• Seminal fluid is thick, yellowish, and alkaline.

• It contains mucus, fructose, a coagulating enzyme, ascorbic acid, and prostaglandins.

• Accessory glands:

1.seminal vesicle

2.prostate gland

3.bulbourethral gland

Seminal Vesicle

Seminal vesicle:• A pair of glands that secrete a liquid

component of semen into the vas deferens. • Secretion is alkaline• Contains fructose, asorbic acid, coagulating

enzyme, prostaglandin

Prostate gland:• Location- surrounds and opens into the urethra where it

leaves the bladder. • Secretion- slightly alkaline fluid that activates the sperm

and prevents them from sticking together

• Prostate problems are common in males over 40.

• Prostate cancer is one of the most common cancers in men.

Prostate

Bulbourethral gland (Cowper’s gland): • Location- paired glands that lie beneath the prostate• Secretion- a thick, clear alkaline mucous that drains into

the membranous urethra. • Function- It acts to wash residual urine out of the urethra

when ejaculating semen-- raises pH; neutralizes acidity of urine.

Bulbourethral gland

• Ejaculation propels sperm from the epididymis to the vas deferens.• The vas deferens run from the scrotum and

behind the urinary bladder.

•Here each vas deferens joins with a duct from the seminal vesicle to form an ejaculatory duct.

• The ejaculatory ducts open into the urethra.• The urethra drains both the excretory and

reproductive systems.

Ejaculation

• A male usually ejaculates about 2 – 5 mL of semen; each milliliter containing about 50 – 130 million sperm.

– Bulbourethral fluid also carries some sperm released before ejaculation.• This is one of the reasons why the

withdrawal method of birth control has a high failure rate.

Ejaculate

Spermatogenesis

Mature Spermatozoa

tail

mitochondria

nucleus

acrosomehead

Seminiferous Tubules

spermatogonium

1º spermatocyte

2º spermatocyte

spermatidsSertoli cell

spermatozoa

Seminiferous Tubules

Seminiferous Tubules

Sperm Maturation & Development

Hormones Involved in Spermatogenesis

• Gonadotropin Releasing Hormone (GnRH)• Follicle Stimulating Hormone (FSH)• Interstitial Cell Stimulating Hormone (ICSH=LH)• Testosterone• Inhibin• ABP

HypothalamusHypothalamusHypothalamusHypothalamus

Anterior PituitaryAnterior PituitaryAnterior PituitaryAnterior Pituitary

GnRHGnRH

FSHFSHICSHICSH

Hormonal Control of Spermatogenesis

Interstitial CellsInterstitial CellsInterstitial CellsInterstitial Cells

ICSHICSH

TestosteroneTestosterone

Hormonal Control of Spermatogenesis

Sertoli CellsSertoli CellsSertoli CellsSertoli Cells

TestosteroneTestosterone

SpermatogenesisSpermatogenesis

FSHFSH

InhibinInhibin

Hormonal Control of Spermatogenesis

Feedback Inhibition

InhibinInhibinActs on anterior pituitaryActs on anterior pituitaryInhibits FSH productionInhibits FSH production

TestosteroneTestosteroneActs on hypothalamusActs on hypothalamusInhibits GnRH productionInhibits GnRH production

Hormonal Control of Spermatogenesis

Some Other Effects of Testosterone

muscle and bone growthmuscle and bone growthfacial and pubic hair growthfacial and pubic hair growth

thickening of vocal cordsthickening of vocal cordsgrowth of pharyngeal cartilagegrowth of pharyngeal cartilage

hair follicle effectshair follicle effectsstimulates sebaceous glandsstimulates sebaceous glands

Increased BMRIncreased BMR

Vasectomy

Female Female Reproductive SystemReproductive System

cervix

vagina

fimbriae

uterine tube

ovary

uterus

bladder

urethra

clitoris

l. minora

l. majora

Female Reproductive System

Internal reproductive:

• Vagina• Cervix• Fallopian tube

(uterian tube/oviducts)• Fimbrae• Ovary• Uterus

- Endometrium- Myometrium- Perimetrium

cervixvagina

fimbriae

uterine tube

ovary

uterus

endometrium

myometrium

perimetrium

Fimbrae & Fallopian Tube

Oogenesis in the Ovary

OogenesisOvary- contains 400,000 oocytes; release

about 500 in a lifetime• Ovary- under influence of FSH. The

follicles mature every 28 days• Primary follicle produces estrogens• And primary oocyte completes its 1st

division produces 2ndary oocyte and polar body

Oogenesis• Aprox 1/2 way through the 28 day cycle the

follicle reaches the mature Vesticular or Graffian follicle stage.

Oogenesis

• Estrogen levels rise and release LH and FSH and triggers ovulation.

Oogenesis• The 2ndary oocyte travels down the uterine

tube to the uterus.• If fertilized by sperm, it will produce a zygote

Ovum in uterine tube

Ectopic Pregnancy

Ovarian Cyst

Endometriosis

Oogenesis

Hormones Involved in the Female Reproductive Cycle

Gonadotropin Releasing Hormone (GnRH)Gonadotropin Releasing Hormone (GnRH)Follicle Stimulating Hormone (FSH)Follicle Stimulating Hormone (FSH)

Luteinizing Hormone (LH)Luteinizing Hormone (LH)EstrogenEstrogen

ProgesteroneProgesteroneInhibinInhibinRelaxinRelaxin

HypothalamusHypothalamusHypothalamusHypothalamus

Anterior PituitaryAnterior PituitaryAnterior PituitaryAnterior Pituitary

GnRHGnRH

FSHFSHLHLH

Female Hormonal Cycle

Follicle CellsFollicle CellsFollicle CellsFollicle Cells

LHLH

EstrogenEstrogen

FSHFSH

Female Hormonal Cycle

The Uterine Cycle

Hormone Fluctuation

Some Other Effects of Some Other Effects of EstrogenEstrogen

• breast development• external genitalia growth• bone growth• fat deposition• Increase protein anabolism• Decrease blood cholesterol• Facilitate calcium uptake• Promotes hydration of skin• Feminizes brain

Menopause: cessation of ovarian and menstrual cycles.• Usually occurs between ages 46 and 54.

• Due to ovaries decreased responsiveness to gonadotropins.

Menopause affects:

• changes in sexual desire

• triggers mood swings

• causes debilitating hot flashes

• may lead to bone and heart problems

• short-term memory loss

• insomnia

•Mammary glands.• Are present in both males and females.

• Are not a component of the reproductive system.

• Contain epithelial tissue that secrete milk.

•Milk drains into a series of ducts opening at the nipple.

Mammary Gland

Life’s Greatest MiracleLife’s Greatest Miracle

• http://www.pbs.org/wgbh/nova/miracle/program.html

INQUIRYINQUIRY

1. Where are sperm cells formed within the testes?

2. What portion of the sperm contains 23 chromosomes?

3. What 3 accessory glands produce seminal fluid?

4. What is the term for the primary human sex organs?

5. What structure is formed following ovulation?

6. What hormones are produced from the corpus luteum?

7. List several effective means for preventing conception.