1. Chapter 46
Animal Reproduction

2. I. Asexual Reproduction
Creation of new individuals whose genes all come from one parent

3. A. Types Fission – separation of parent into 2 individuals
Budding – new individuals from an existing one
Fragmentation – breaking the body into several pieces / regeneration
Parthenogenesis – egg develops without being fertilized

4. B. Benefits No mate needed Lots of offspring fast
Advantageous in stable, favorable environments

5. II. Mechanisms of Sexual Reproduction
Both types use pheromones to attract mates

6. A. Internal Fertilization
Fertilization occurs in or near the female reproductive system
Requires cooperative behavior and complex reproductive systems
Produces fewer offspring but greater protection and care of young is seen

7. B. External Fertilization
Eggs are released and fertilized in the environment
Need an environment where eggs will not dry out
Timing is crucial
Produce more zygotes but less survive

8. C. Variations Complex : flatworm, insects (spermatatheca)
Simple : polychaete where gametes develop from cells in the coelom
Many use a cloaca

9. Flatworm

10. Insects

11. III. Mammalian / Human Reproductive System

12. A. Male Testes – male gonad
Seminiferous tubules – make up most of the testes / lots of small coils / sperm made here
Leydig Cells – produce androgens, in testes
Scrotum – sac that holds the testes
Epididymis – tube from the seminiferous tubules to the vas deferens / 6m long / sperm gain mobility here
Vas Deferens – carry sperm from the epididymis behind the bladder up to the ejaculatory duct
Ejaculatory Duct – opens to urethra and goes out

13. Male (cont) 3 Glands That Together Make Semen
a. Seminal vesicles - 60%, yellow, thick, alkaline, mucus, fructose, coagulating enzyme, ascorbic acid, prostaglandins (thins uterine mucus and cause contractions)
b. Prostate gland – thin, milky, anticoagulant enzyme, citrate
c. Bulbourethral gland – before ejaculation, clear mucus, neutralizes urine from urethra
Penis – erectile tissue fills with blood and injects semen
Glans Penis – head, thin skin
Prepuce - foreskin

16. B. Female
Ovary – female gonad / has lots of follicles (egg and nourishing follicle cells / turns into corpus luteum) / follicles produce estrogen
Oviduct / Fallopian Tubes – tube leading from ovary to uterus / cilia
Uterus – thick muscular organ for holding the baby
a. Endometrium – lining of uterus / rich in blood vessels
b. Cervix – neck of uterus
Vagina – forms birth canal
a. Hymen – covers vaginal opening

17. B. Female (cont)
Labia minora/majora – flaps of skin that border the vestibule
Clitoris – mostly erectile tissue with lots of nerve endings
Bartholin’s Glands – secrete mucus / near vaginal opening

20. IV. Formation of Sperm and Egg

21. A. Spermatogenesis Occurs in the seminiferous tubules / continuous
Spermatogonia are the special diploid cells
Starts on the edge of the tubule and moves towards the lumen
Spermatogonia – Primary Spermatocyte – Spermatids – Sperm (Spermatocyte)
65-75 days

24. B. Oogenesis Occurs in the ovary and fallopian tubes
Oogonia are the specialized diploid cells
Oogonia multiply and begin meiosis I but stop at prophase I (primary oocyte). Stay this way till puberty.
FSH enters and stimulates a follicle to grow and a primary oocyte to complete meiosis I and start meiosis II but stop at metaphase II (secondary oocyte)

25. B. Oogenesis (cont) The secondary oocyte is released during ovulation
Meiosis II completes after fertilization occurs
* Uneven cytoplasm distribution results in polar bodies

28. V. Hormones and Reproduction

29. A. Male Hormones
Androgens (Testosterone) – produced by leydig cells in testes
- increase primary and secondary characteristics
- increase aggressiveness, deep voice, hair, muscles, etc.

31. B. Female Hormones Menstrual vs. Estrous Cycle
- Both Cycles: ovulation occurs after endometrium thickens
- Estrous: reabsorb endometrium, pronounced behavior changes, stronger seasonal effects, estrus, does not occur in primates
Coordination of Cycles and Hormones
Menopause – no longer respond to gonadotropins

32. B. Female Hormones Hormones a. GnRH – gonadotropin releasing hormones
- Made by hypothalamus / uses estrogen levels to regulate
- stimulates LH and FSH production by pituitary
- estrogen and progesterone together stop it
b. FSH – follicle stimulating hormone
- induces follicular phase
c. LH – luteinizing hormone
- causes change to corpus luteum

33. - Low amounts of LH and FSH
- Receptors for FSH not LH
- FSH stimulates follicle growth
- Follicle produces estrogen which thickens the endometrium and inhibits LH and FSH
- Later lots of estrogen increases GnRH production of LH and FSH in high amounts
Now the follicle has LH receptors and ovulation occurs (secondary oocyte)

34. - Left over LH changes follicle to corpus luteum
- Corpus luteum secretes estrogen and progesterone
- Together they stop production of GnRH which stops LH and FSH
- This keeps the endometrium happy
- Corpus luteum disintegrates and estrogen and progesterone drop allowing LH and FSH to be produced
8. - Causes spasms in uterus and endometrium sheds

35. B. Female Hormones
So what if there is a fertilized embryo implanted into the endometrial lining?
- HCG (human chorionic gonadotropin) is produced by the embryo which keeps the corpus luteum intact.
- Eventually the placenta produces the needed estrogen and progesterone

36. VI. Pregnancy
38-40 weeks

37. A. First Trimester 1. Fertilization occurs in fallopian tubes
Cleavage (24 hours)
Ball of cells is now in the uterus (3-4 days)
Blastocyst (embryo) 1 week / 5 more days to implant
2-4 weeks it get nutrients from endometrium and then the placenta forms
Organogenesis occurs and most organs are formed by 8 weeks
Mucus plug forms

38. B. Second Trimester Movement (20 weeks) Continued growth
HCG stops and corpus luteum falls apart / placenta secretes the necessary progesterone

39. C. Third Trimester
High estrogen levels trigger oxytocin receptors on the uterus
Oxytocin produced by the fetus and mom trigger contractions
Oxytocin also trigger the placenta to make prostaglandins to help too
- positive feedback, more stress more hormones
4. Birth : dilation, birth, afterbirth

41. VII. Contraceptives Rhythm Method Barrier Methods / Condom, diaphragm
IUD
Withdrawal
Birth Control Pills / Synthetic Estrogen and Progesterone / Both stop GnRH, estrogen stops FSH, Progesterone stops LH
Sterilization / tubal ligation, vasectomy
Abstinence