Chapter 46 Animal Reproduction

1. Chapter 46 Animal Reproduction

2. Overview of sexual reproduction

3. Both asexual and sexual reproduction occur in the animal kingdom sexual reproduction : fusion of haploid gametes to form a zygote, fertilized eggs Female gamete: ovum Male : spermatozoon

4. Diverse mechanisms of asexual reproduction enable animals to produce identical offspring invertebrate: fission budding fragmentation and regeneration

5. Figure 46.0x1 Utethesia ornatrix mating

6. Figure 46.0x2 Red beetles mating

7. Figure 46.1 Two from one: asexual reproduction of a sea anemone (Anthopleura elegantissima)

8. Figure 46.x1 Aphid giving live birth

9. reproductive cycle and pattern vary extensively • among animals • Most animals shows definite cycles in reproductive • activity • 2. Controlled by hormonal and environmental cues (temperature, rainfall, day length and lunar cycle) • parthenogenesis: eggs develop without fertilization • fig 46.2

10. Figure 46.2 Sexual behavior in parthenogenetic lizards (a)

11. 3. Reproduction may alternate between sexual and asexual hermaphrodite: individuals has both male and female reproductive system( for sessile and burrowing animals) sequential hermaphrodite protogenous : female first protandrous: male first figure 46.3

12. Figure 46.3 Sex reversal in a sequential hermaphrodite

13. Mechanisms of sexual reproduction fertilization: Internal fertilization External fertilization

14. Internal and External fertilization both depend on • mechanisms ensuring that mature sperm encounter • fertile eggs of the same species • Internal fertilization • a. require cooperative behavior,lading to copulation • b. require sophisticated reproductive system • 2. External fertilization • a. an environment where eggs can develop without • desiccation or heat stress

15. Figure 46.0 Frogs mating

16. Figure 46.4 The release of eggs and external fertilization

17. Species with internal fertilization usually produce fewer zygotes but provide more parental protection than species with external fertilization a. External fertilization less protection for eggs and fertilized zygotes b. Internal fertilization protection by: egg shells develop within reproductive tract pouches for marsupials

18. Figure 46.x2 Sea urchin sperm fertilizing an egg

19. Figure 46.5 Parental care in an invertebrate

20. Complex reproductive systems have evolved in animal phyla( phylum Annelida) • Polychaete( 多毛綱 ) separate sex, but no distinct gonads  eggs and sperms develop from undifferentiated linings of the coelom  gametes release from body wall and fill the coelom as they mature

21. 2. Flat worm ( Phylum Platyhelminthes)  hermaphroditic  sperms may ejected to female reproductive system of another individual

22. Figure 46.6 Reproductive anatomy of a parasitic flatworm

23. Insects  separate sex with complex reproductive system  sperm develop in a pair of testes and stored in the seminal vesicles  eggs develop in a pair of ovaries  female may store sperms in spermatheca

24. Figure 46.7 Insect reproductive anatomy

25. Mammalian reproductive system

26. 尿囊 貯精囊 輸精管 前列腺 尿道 尿道球腺 副睪 龜頭 睪丸 陰囊 包皮 Figure 46.8 Reproductive anatomy of the human male

27. 尿囊 貯精囊 前列腺 尿道球腺 尿道 輸精管 陰囊 副睪 睪丸 龜頭 Figure 46.8 Reproductive anatomy of the human male

28. Spermatogenesis The production of mature sperm cells  a ejaculation of human male contain 100-650 million sperms

29. Figure 46.11 Spermatogenesis

30. Figure 46.11x Spermatogenesis: Seminiferous tubules (left), sperm in semen (right)

31. Figure 46.12 Structure of a human sperm cell

32. 輸卵管 卵巢 子宮 尿囊 子宮頸 尿道 陰道 陰蒂 尿道球腺 大( 小)陰唇 Figure 46.9 Reproductive anatomy of the human female

33. Figure 46.9 Reproductive anatomy of the human female

34. Oogenesis  The development of ova( mature, unfertilized egg cells)  Egg cells stays at prophase of meiosis I until puberty

35. Birth to puberty Stimulation of FSH Figure 46.13a Oogenesis

36. Figure 46.9x Ovary (left) and follicle (right)

37. Figure 46.10 Ovulation

38. Figure 46.13b Oogenesis

39. 雌激素 黃體激素 Figure 46.15 The reproductive cycle of the human female shedding of endothelium lining

40. Differences of Oogenesis and spermatogenesis • Cytokinessis of meiotic division in oogenesis is • unequal ( polar body degenerate) • 2. Mitosis continues thought the male’s life • 3. Oogenesis has long ‘resting period’

41. A complex interplay of hormone regulates reproduction

42. The male pattern • Androgen ( 雄激素)---- testosterone • Produced by ledig cells of testes • Responsible for 1st and 2nd sex characteristics  development of vas deferentia, development of external reproductive structure, sperm production • The aggressiveness of male behavior is enhanced by androgen

43. 下視丘 腦下垂體 濾泡刺激激素 Figure 46.14 Hormonal control of the testes

44. The female pattern • Ovulation occurs during menstrual cycle( shedding of • endothelium lining of uterus) or estrous(endothelium • lining cycle • More pronounced behavior change for estrous cycle than menstrual cycle Average of 28 days for menstrual cycle • Ovaries lose their response to FSH and LH during menopause (age 46-54)

45. Embryonic and fetal development occur during pregnancy in human and other placental animals

46. Figure 46.16 Formation of the zygote and early postfertilization events

47. Reproductive Immunology Interference of immune response by trophoblast: 1. Produce chemical signal induce suppressor T cell which prevent other T cell from foreign tissue 2. Secret enzyme that break down tryptophan that is necessary for T cell survival 3. A mouse protein produced by trophoblast protect embryo from been attacked by complement

48. Figure 46.17 Placental circulation

49. 5 weeks 14 weeks 20 weeks Figure 46.18 Human fetal development

50. Figure 46.19 Hormonal induction of labor