1. Animal Reproduction

2. Reproduction is asexual or sexual –asexual reproduction offspring genetically identical to parent and siblings saves costs of sexual reproduction resulting population lacks genetic variability

3. Animal Reproduction Reproduction is asexual or sexual –asexual reproduction various methods –budding »outgrowth from body of parent –regeneration »regrowth of lost body parts or whole organisms

4. budding of hydra regeneration of a sea star Figure 43.1

5. parthenogenesis & vivipary in aphid

6. Animal Reproduction Reproduction is asexual or sexual –asexual reproduction various methods –parthenogenesis »production of offspring from unfertilized eggs »may require mating behavior to stimulate development

7. parthenogenesis in whiptail lizards Figure 43.2

8. Animal Reproduction Reproduction is asexual or sexual –sexual reproduction offspring differ genetically from parents involves significant cost –gametogenesis –mating (getting gametes together) –fertilization (syngamy - gamete fusion)

9. Animal Reproduction Reproduction is asexual or sexual –sexual reproduction offspring differ genetically from parents involves significant cost resulting population exhibits genetic variability

10. Animal Reproduction Reproduction is asexual or sexual –sexual reproduction - genetic variability combines genetic contributions from male and female parents gamete genomes contain recombined chromosomes –crossing over (prophase I) –independent assortment (metaphase I)

11. Animal Reproduction Reproduction is asexual or sexual –sexual reproduction alternates the halving and doubling of genomes –meiosis reduces 2n genome to 1n –fertilization combines two 1n gametes

12. Animal Reproduction meiosis is part of gametogenesis –gametogenesis occurs in the primary sex organs - the gonads motile sperm are produced in testes non-motile eggs (ova) are produced in ovaries

13. Early stages of spermatogenesis and oogenesis Figure 43.3

14. Animal Reproduction gametogenesis –germ cells enter the gonads during embryonic development –germ cells divide mitotically to produce spermatogonia or oogonia –spermatogonia and oogonia divide mitotically to produce primary spermatocytes and primary oocytes –meiosis produces spermatids and ootids

15. Animal Reproduction spermatogenesis –meiosis I divides a primary spermatocyte produces two secondary spermatocytes –haploid –connected due to incomplete cytokinesis –meiosis II divides secondary spermatocytes produces four linked spermatids spermatids develop into sperm

16. complete spermatogenesis Figure 43.3

17. Animal Reproduction oogenesis –primary oocyte enters prophase I arrests development at prophase I remains in prophase I for some time grows & accumulates nutrients, energy, RNA, ribosomes, organelles

18. human gametes differ in size

19. Animal Reproduction oogenesis –primary oocyte resumes meiosis I asymmetric division produces two cells –secondary oocyte –first polar body secondary oocyte divides asymmetrically in meiosis II –ootid –second polar body

20. complete oogenesis, minus pauses Figure 43.3

21. Animal Reproduction oogenesis –timing of meiosis and egg development varies secondary oocyte pauses in development prior to meiosis II meiosis II may occur after expulsion from the ovary human ova completes meiosis II after fertilization

22. Fertilization sperm/egg recognition –recognition molecules ensure that sperm interact with eggs of the same species jelly layer activates acrosome acrosomal enzymes digest jelly layer acrosomal process bears bindin proteins plasma membrane bears bindin receptors

23. sea urchin sperm/egg recognition Figure 43.4

24. Fertilization mammalian sperm/egg recognition –sperm capacitation occurs in female reproductive tract –superficial sperm enzymes digest cumulus –zona pellucida glycoproteins bind sperm head recognition proteins –acrosomal enzymes digest zona pellucida –plasma membrane proteins bind sperm adhesion proteins

25. (follicle cells) (glycoprotein) mammalian barriers to sperm entry Figure 43.5

26. fast block to polyspermy in sea urchin: prevents entry by multiple sperm plasma membrane electrical potential rapid Na + influx

27. sperm entry Ca 2+ release exocytosis fertilization envelope slow block to polyspermy Figure 43.6

28. Fertilization egg activation –mammals calcium release from ER cortical granule fusion removal of sperm-binding proteins metabolic activation –increased cytoplasmic pH –increased O 2 consumption –increased protein synthesis nuclear fusion ~12 h after sperm entry

29. simultaneous hermaphroditic fertilization

30. Animal Reproduction sexual identity in animals –many animals are dioecious –other animals are monoecious (hermaphroditic) simultaneous hermaphrodites sequential hermaphrodites

31. fertilization fusion of sperm and egg –produces zygote –requires sperm & egg to be in close proximity

32. release of sperm and eggs

33. mating behavior external fertilization –release of gametes into aquatic environment –chance meeting of egg & sperm synchronized release by sessile animals simultaneous release by motile animals

34. simultaneous release of sperm & eggs

35. mating behavior internal fertilization –protects sperm from desiccation spermatophores - sperm containers –released to environment –inserted into female genital opening

36. mating behavior internal fertilization –protects sperm from desiccation copulation –direct transfer of sperm –requires accessory sex organs »penis »vagina or cloaca

37. development site of development varies –oviparous egg bearing external development –viviparous live bearing internal development in uterus –ovoviviparous development in eggs retained within body

38. human reproductive system male organs produce & deliver sperm –semen sperm –produced in testes –stored in epididymis –transported through vas deferens –combined with fluids –ejaculated through urethra during copulation

39. human reproductive system male organs produce & deliver sperm –semen bulbourethral fluid –pH buffer & lubricant seminal fluid –fructose, prostaglandins, mucus/protein prostate fluid –modifies uterine environment –clots seminal fluid

40. male primary and accessory sex organs Figure 43.8

41. sperm production in seminiferous tubules Figure 43.9

42. human reproductive system sperm development –within the scrotum –within seminiferous tubules developing sperm are engulfed by Sertoli cells developing sperm migrate from periphery to lumen of tubule mature sperm are released into lumen and travel to epididymis Leydig cells produce testosterone

43. Spermatogenesis Figure 43.9

44. human reproductive system hormonal control of sperm development –gonadotropin-releasing hormone (GnRH) from hypothalamus, stimulates –luteinizing hormone (LH) »from anterior pituitary, stimulates -testosterone release from Leydig cells

45. human reproductive system hormonal control of sperm development –spermatogenesis is controlled by follicle-stimulating hormone (FSH) & testosterone –on Sertoli cells

46. control of male sex hormone production Figure 43.10 [remember to study this figure and explanatory slides associated with it]

47. oviduct cilia

48. human reproductive system female sex organs –ovary produces eggs –eggs are released into oviduct –oviduct transports egg to uterus –embryo implants in uterine wall –cervix retains uterine contents during pregnancy; dilates during birth –sperm enter, baby departs through vagina

49. female primary and accessory sex organs Figure 43.11

50. human reproductive system female reproductive cycles –ovarian cycle~28 days production of a secondary oocyte –surrounded, supplied by follicle cells –growth, maturation, first meiotic division –release from ovary increased hormone production –follicle cells of corpus luteum –produces estrogen & progesterone

51. stages of the ovarian cycle Figure 43.12 meiosis

52. human reproductive system female reproductive cycles –uterine cycle growth of endometrium – ~days 5-19 of ovarian cycle –prepares for implantation breakdown of endometrium – ~end of ovarian cycle –expelled from body through vagina

53. human reproductive system hormonal control of reproductive cycles –GnRH from hypothalamus stimulates –gonadotropins (LH & FSH) from anterior pituitary stimulate –estrogen from ovary

54. human reproductive system hormonal control of reproductive cycles –~ 5 days before start of ovarian cycle anterior pituitary increases gonadotropins follicle matures & increases estrogen estrogen stimulates endometrial growth estrogen feedback reverses to boost LH LH causes release of secondary oocyte

55. human reproductive system hormonal control of reproductive cycles –corpus luteum secretes estrogen & progesterone maintain endometrial growth inhibit gonadotropin release to inhibit follicle development –without fertilization, corpus luteum degenerates

56. Figure 43.13

57. hormonal control of ovarian and uterine cycles Figure 43.14 [remember to study this figure and explanatory slides associated with it]

58. human reproductive system hormonal control of reproductive cycles –with fertilization human chorionic gonadotropin (hCG) –is produced by embryo –sustains corpus luteum gradually, embryo derived cells –produce estrogen & progesterone –prevent anterior pituitary from releasing gonadotropins