1. Copyright © 2010 Pearson Education, Inc. Chapter 20 Is There Something in the Water? Reproductive and Developmental Biology

2. Copyright © 2010 Pearson Education, Inc. Chapter 20 Section 1 Principles of Animal Reproduction

3. Copyright © 2010 Pearson Education, Inc. 20.1 Principles of Animal Reproduction Two main types of reproduction 1.Asexual reproduction 2.Sexual reproduction Asexual Reproduction  one parent produces offspring that are genetically identical to the parent

4. Copyright © 2010 Pearson Education, Inc. 20.1 Principles of Animal Reproduction Two main types of asexual reproduction  Binary fission – cells break away from parent to form offspring (e.g., sponges)  Budding – daughter cell remains attached to parent and breaks away when mature (e.g., hydra)

5. Copyright © 2010 Pearson Education, Inc. 20.1 Principles of Animal Reproduction – Sexual Reproduction  Sexual reproduction combines genomes of two individuals to create variable offspring  Females = individuals that produce large gametes (sex cells)  Males = individuals that produce small gametes  Gonads = Organs that produce gametes  Male gonad = testes  Female gonad = ovaries

6. Copyright © 2010 Pearson Education, Inc. 20.1 Principles of Animal Reproduction Methods of fertilization 1.Internal fertilization – sperm deposited by copulation in or near female reproductive tract.  Mammals, birds, reptiles, and sharks use internal fertilization. 2.External fertilization – eggs laid, male deposits sperm over eggs (usually in water). Most fish and amphibians use external fertilization.  Very susceptible to contaminants

7. Copyright © 2010 Pearson Education, Inc. 20.1 Principles of Animal Reproduction  Developing frogs are extremely sensitive to environmental chemicals  Eggs develop in water  Embryos absorb toxins easily  Frogs are declining globally Figure 20.2 Environmental Contaminants and Sexual Reproduction

8. Copyright © 2010 Pearson Education, Inc. 20.1 Principles of Animal Reproduction - Endocrine Disruptors  Man-made chemicals alter endocrine regulation  interferes with normal gonad development.  Male amphibians have been feminized.  These chemicals affect animals living in water.  Are humans affected by drinking contaminated water?

9. Copyright © 2010 Pearson Education, Inc. End Chapter 20 Section 1 Principles of Animal Reproduction

10. Copyright © 2010 Pearson Education, Inc. Chapter 20 Section 2 Part A Human Reproduction: Males

11. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Male Reproductive Anatomy  Penis  Contains spongy erectile tissue  Fills with blood to cause erection  Testes  Inside scrotum  Produce sperm and testosterone Figure 20.4

12. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Male Reproductive Anatomy  Accessory Glands  Prostate & seminal vesicles  Secrete fructose, mucous Figure 20.4  Testes  Inside scrotum  produce sperm and testosterone  Epididymis  Stores sperm  Vas deferens & urethra

13. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Endocrine Disruptors & Humans  Men  Most common cause of male infertility is the inability to produce healthy sperm.  Sperm counts are declining globally

14. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Gametogenesis = production of gametes (germ cells)  Involves meiosis  Reduces number of chromosomes by ½  Human body cells contain 46 chromosomes, gamete contain 23  (see chapter 5 for review)  Male and female gametes undergo further development to become functional

15. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Spermatogenesis Figure 20.6 Seminiferous tubules = functional unit of testis Contain developing sperm cells Sertoli cells – nurse cells for sperm Leydig cells outside seminiferous tubules Make and release testosterone

16. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Cell types in Spermatogenesis Figure 20.6 Spermatogonia Stem cells Divide by mitosis Primary spermatocytes Enter Meiosis I Secondary spermatocytes Enter meiosis II Spermatids Undergo spermiation Cytodifferentiation Spermatozoa

17. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Spermatozoa Structure Figure 20.6 Head Condensed nucleus Acrosome Contains enzymes for fertiliztion Midpiece Lots of mitochondria Tail Flagellum for swimming

18. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction - Male Infertility Human infertility and endocrine disruptors  90% of male infertility is related to problems with sperm formation or production  Low sperm counts  Improperly shaped sperm  Low motility  Chemical exposure (e.g., pesticides) can decrease sperm viability  Male infertility also increases with alcohol and drug use, including cigarettes  Sperm counts declining globally since WWII

19. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Animation—The Male Reproductive System PLAY

20. Copyright © 2010 Pearson Education, Inc. End Chapter 20 Section 2 Part A Human Reproduction: Males

21. Copyright © 2010 Pearson Education, Inc. Chapter 20 Section 2 Part B Human Reproduction: Females

22. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Female Reproductive Anatomy Figure 20.5  External genitalia  Labia majora & labia minora  clitoris  Reproductive tract  Vagina  Uterus  Paired oviducts  Fertilization  Separate urethral opening

23. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Female Reproductive Anatomy Figure 20.5  Ovaries  Endocrine  Estrogen  Progesterone  Produces gametes  Follicle contains:  Egg  Endocrine cells

24. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Endocrine Disruptors & Humans  Women  DES is a drug that acts as an endocrine disruptor.  Given to women to prevent premature delivery  Daughters of women who took DES have a higher rate of infertility.

25. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Oogenesis Figure 20.7 Two parts 1.Oocyte development 2.Follicular development

26. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Oocyte Development Figure 20.7 All oogonia (stem cells) become primary oocytes during her (the mother’s) embryonic development Each month during menstrual cycle Primary oocytes enter meiosis I -> secondary oocytes Secondary oocytes complete meiosis II at fertilization Polar bodies will deteriorate

27. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Follicular Development Figure 20.7 Follicles include oocytes and surrounding endocrine cells Primary follicle stores primary oocytes until use FSH causes development to secondary follicle and then Graffian follicle (both with secondary oocyte) Secrete estrogen LH causes ovulation Follicle become corpus luteum Secretes estrogen & progesterone

28. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction The Menstrual Cycle  Changes in the uterine endometrium  Prepares endometrium for pregnancy  Regulated by:  Pituitary FSH & LH  Ovarian estrogen & progesterone Figure 20.8

29. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction The Menstrual Cycle  Days 1-4  Menstruation  Only FSH elevated  causes new follicle to grow  Days 5-14  FSH causes follicle to grow & release estrogen  Estrogen causes endometrium to grow Figure 20.8

30. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction The Menstrual Cycle  Day 14  Surge of LH causes ovulation & corpus luteum formation Figure 20.8

31. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction The Menstrual Cycle  Day 14-28  FSH & LH cause ovary to secrete estrogen & progesterone  Prepares for pregnancy  Corpus luteum dies at end of cycle  Results in collapse of endometrium and start of menstruation Figure 20.8

32. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Regulating The Menstrual Cycle Regulation involves both positive & negative feedback loops Figure 20.9  High estrogen causes positive feedback on LH  Leads to LH surge  High progesterone causes negative feedback on LH & FSH

33. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Pregnancy  If the egg is fertilized, embryo secretes human chorionic gonadotropin (hCG)  hCG mimics LH and keeps corpus luteum alive  Progesterone maintains endometrium during pregnancy Birth Control Pills  Mimic pregnancy by providing estrogen and progesterone  prevent ovulation by blocking LH surge Figure 20.9

34. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Female Infertility  One cause of female infertility is endometriosis  a condition where the endometrial cells can attach to the ovaries & oviducts  also grow and shed during menstrual cycle  Can cause damage and scarring to ovarian tissue  Can disrupt ovulation  Painful  May be related to exposure to environmental chemicals like DEHP

35. Copyright © 2010 Pearson Education, Inc. 20.2 Human Reproduction Animation—The Female Reproductive System PLAY

36. Copyright © 2010 Pearson Education, Inc. End Chapter 20 Section 2 Part B Human Reproduction: Females

37. Copyright © 2010 Pearson Education, Inc. Chapter 20 Section 3 Human Development Chapter 20 Section 4 Is the Water Safe to Drink?

38. Copyright © 2010 Pearson Education, Inc. 20.3 Human Development Fertilization 1.Sperm penetrate follicle cells 2.Sperm head binds to zona pellucida 3.Acrosome enzymes released 4.Egg & sperm membranes fuse 5.Sperm nucleus enters egg cell Figure 20.11

39. Copyright © 2010 Pearson Education, Inc. 20.3 Human Development Endocrine Disruptors and Fertilization  Industrial solvents can mimic hormones and interfere with sperm development and fertilization.  Misshapen sperm cannot swim effectively and are unable to fertilize egg.  Males exposed to solvents, working as mechanics or dry cleaners, have a larger number of abnormal sperm.  While effect on adults lowers fertility, effects on developing fetus is more severe

40. Copyright © 2010 Pearson Education, Inc. 20.3 Human Development Human Embryonic Development  Human zygote undergoes a series of cleavages to produce an embryo  Embryo is stage from zygote until body structures appear  Blastocyst = hollow ball of cells  Gastrula = tissue layers start to appear Figure 20.12

41. Copyright © 2010 Pearson Education, Inc. 20.3 Human Development - Human Embryonic Development Gastrula has 3 tissue layers  Endoderm – forms digestive & respiratory  Mesoderm – forms muscles, skeleton, excretory, circulatory, & gonads  Ectoderm – forms skin, nervous & sensory  Growth of a particular tissue or organ relies on chemical stimulus  Very sensitive to chemical disruption

42. Copyright © 2010 Pearson Education, Inc. 20.3 Human Development Development of Human Reproductive Organs Table 20.3 Male & female organs develop from same embryonic precursors Hormonal signals cause development of male and female reproductive organs

43. Copyright © 2010 Pearson Education, Inc. 20.3 Human Development Endocrine Disruptors & Reproductive Organs Table 20.3 Chemicals can pass from mother’s blood to fetus Common herbicides & fungicides can cause cryptorchidism Undescended testes 2 to 4 % of human males are now born with undescended testes

44. Copyright © 2010 Pearson Education, Inc. 20.3 Human Development Pregnancy or Gestation  A placenta must develop to sustain pregnancy  Embryo blastocyst implants in the wall of the uterus  Maternal and fetal blood supplies are closely intertwined, allowing exchange of nutrients and wastes  9 week old fetus has all its limbs and organs in place  Environmental chemicals can seriously effect embryo & fetus

45. Copyright © 2010 Pearson Education, Inc. 20.3 Human Development Childbirth  Decreasing estrogen in late pregnancy induces oxytocin receptors to form in uterine muscle  Hormone oxytocin uses a positive feedback loop to induce labor. Figure 20.15

46. Copyright © 2010 Pearson Education, Inc. 20.4 Is the Water Safe to Drink? Human correlations with endocrine disruptors  abnormal sperm  lower sperm counts  decreased fertility  cryptorchidism  endometriosis  uterine abnormalities EPA requires monitoring of municipal water supplies.  But it’s unclear what chemicals to monitor and what is a safe level of chemicals

47. Copyright © 2010 Pearson Education, Inc. Chapter 20 Section 3 Human Development Chapter 20 Section 4 Is the Water Safe to Drink?

48. Copyright © 2010 Pearson Education, Inc. End Chapter 20 Section 2 Human Reproduction