Chapter 26 Reproduction

Question 1

What is dimorphism? How are zygotes produced? What are the two different gametes and where are they formed?

Answer 1

1. Dimoprhism: physically distinct males and females
2. when eggs and sperm fuse theyform zygotes
3. Male gonad: testes which form sperm
   Female: ovaries which form eggs

Question 2

How many chromosomes do humans have? How many are autosomal? How many are sex?

Answer 2

1. 46
2. 22pairs
3. 1 pair: XX or XY

Question 3

How many chromosomes are in each sperm and egg?

Answer 3

1. Sperm 23
2. Egg: 23
   * Zygote has 46

Question 4

What chromoeosmes do the sperm and egg have? How can they contribute to either a boy or girl?

Answer 4

1. Females only carry XX chromosomes in their eg
2. Men have either an X or Y chromosome in their sperm

*With this combination there can be either an XX or XY*

Question 5

What are the male and female equivalent structures? What is the bipotential structure for each?

http://media.discovery.lifemapsc.com/pub/uploadedFiles/images/Reproductive_system_development.png

Answer 5

Genital tubercle
Male:Glans penis
Female: clitoris

Urethral folds and groove
Male: shaft of penis
Female: labia minora, opening of vagina and urethra

Labioscrotal swellings
Male: penis shaft and scrotum
Female: labia majora

Gonad (cortex)
Male: regresses
Female: ovary

Gonad (medulla)
Male: testis
Female: regresses

Wolfian duct
Male: epididymis, vas deferens, seminal vesicle
Female: regresses

Mullerian duct
Male: regresses
Female: fallopian tube, uterus, cervix, and upper vagina

Question 6

What are the bipotential tissues?

Answer 6

The Sex-determining Region of Y chromosome (SRY) gene

Gonad: either testis or ovary

Ducts: wolffian or mullerian

Question 7

Because of the SRY gene what happens to the medulla of the bipotential gonad? What are the two cells involved with the sperm? What three things does the wolffian duct develop into? What happens to the mullerian duct?

Answer 7

*This is essentially the development for a male*

1. The medulla develops into the testis
2. a. The sertoli cell: or nurse cell nourishes developing sperm cells
   b. Leydig cell: make and secrete testosterone
3. Epididymis, vas deferens, and seminal vesicle
4. degenerates

Question 8

Because there is no SRY gene, what happens to the cortex of the bipotential gonad? What three thing are developed from the mullerian duct? What happens to the wolffian duct?

Answer 8

1. develops into ovary
2. Vagina, uterus, fallopian tubes
3. degenerates

Question 9

What is the overview for the internal development for females at ten weeks?

Answer 9

1. Gonadal cortex becomes ovary with absence of SRY protein
2. wolffian duct degenerates in absence of testosterone
3. mullerian duct becomes the fallopian tubes, uterus, and upper part of vagina. Because abscence of anti-mulllerian hormone

Question 10

What is the overview for the internal development for males at ten weeks?

Answer 10

1. SRY protein directs the medulla of the bipotential gonad to develop into testis
2. anti mullerian hormone causes the mullerian duct to degenerate
3. testosterone converts wolffian duct into seminal vesicle, vas deferens, and epididymis
4. DHT controles prostate development

Question 11

What is the development of the external genitalia of women?

Answer 11

At ten weeks

• Genital tubercle becomes clitoris
• Labioscrotal swelling becomes folds out

At birth
*in abscence of androgens, external genitalia are feminized*
-labioscrotal swelling is now labia majora
-urethral fold is now labia minora
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-

-

-finish??????????

Question 13

WHat are the sex hormones for males and females?

Answer 13

• *Males**
• testosterone (95% testes/5% adrenal cortex)
• estrogen
• *Females**
• progesterone
• estrogen
• androgens

Question 15

What are the structures of the male reproductive system?

Answer 15

1. **Testes **
2. seminiferous tubule
3. External genitalia
   - penis
   - scrotum
4. Internal genitalia and glands/ducts
   - prostate
   - seminal vesicle
   - bulbourethral
   - epididymis
   - vas deferens

Question 16

What is a vasectomy? How is it done? Does it have negative effects?

Answer 16

1. Vasectomy: common, reliable, permanent male contraception
2. the vas deferens is cut and tied to prevent sperm transport
3. No: it does not efefct testosterone, erections, or sexual pleasure

Question 18

Where does spermatogenesis occur? How is this process done?

Answer 18

1. It occurs in the seminiferous tubule of the testes
2. a. has spermatogonia which are germ cells
   b. sertoli cells nurish and regulate the development of sperm

Question 19

What is the composition of sperm? What amount of sperm signals infertility? What causes infertility?

Answer 19

1. Sperm 1% (40-250million/ml) and accessory gland secretions 99% (1.5-5.0ml)
   - secretions include water, buffers, nutrients and enzymes
2. less than 200million/ml
3. heat, drugs, or anabolic steroids

Question 20

How do spermatozoa propell themselves? How do spermatozoa enter an ovum? what are the componets of spermatozoa?

Answer 20

1. Spermatozoa are propelled by flagella
2. The head of spermatozoa have an acrosome, which releases enzymes that digest the exterior ovum for entry
3. head with enzymes and DNA, long tail, and mitochondria

Question 21

What are the female reproductive structures?

Answer 21

1. ovaries
2. external genitalia
   * *-mons pubis
   - labia majora and minora clitoris**
3. Inner genitalia
   - uterus
   - fallopian tubes
   - vagina

Question 22

Where are oocytes developed?