1. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PowerPoint Lectures for Biology: Concepts and Connections, Fifth Edition – Campbell, Reece, Taylor, and Simon Lectures by Chris Romero Chapter 27 Reproduction and Embryonic Development

2. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Baby Bonanza increased use of fertility drugs –increase in # of multiple births in US

3. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Fertility drugs –sometimes too effective...

4. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings HUMAN REPRODUCTION 27.2 Reproductive anatomy of the human female Both sexes have: –set of gonads where gametes are produced –ducts for delivery of gonads –structures for copulation

5. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings ovaries –Follicles-nurture eggs & produce hormones Oviduct Ovaries Follicles Corpus luteum Wall of uterus Uterus Endometrium (lining of uterus) Cervix (“neck” of uterus) Vagina Figure 27.2A

6. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Oviducts convey eggs to uterus –Where eggs develop Egg cell Ovary LM 200  Figure 27.2B

7. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings uterus opens into vagina –Intercourse...duh! –forms the birth canal

8. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Other structures of female reproductive system Oviduct Ovary Uterus Urinary bladder (excretory system) Pubic bone Urethra (excretory system) Shaft Glans Prepuce Clitoris Labia minora Labia majora Vaginal opening Anus (digestive system) Bartholin’s gland Vagina Cervix Rectum (digestive system) Figure 27.2C

9. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.3 Reproductive anatomy of the human male A man’s testes –Produce sperm Rectum (digestive system) Seminal vesicle Vas deferens Ejaculatory duct Prostate gland Bulbourethral gland Vas deferens Epididymis Testis Scrotum Urinary bladder (excretory system) Pubic bone Erectile tissue of penis Urethra (excretory system) Glans of penis Prepuce Penis Figure 27.3A

10. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Several glands –Contribute to formation of fluid that nourishes and protects sperm Urinary bladder (excretory system) Prostate gland Bulbourethral gland Erectile tissue of penis Vas deferens Epididymis Testis Seminal vesicle (behind bladder) Urethra Scrotum Glans of penis Figure 27.3B

11. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings During ejaculation –Sperm and the nourishing fluid, called semen, are expelled through the penis Sphincter contracts Urinary bladder Urethra region here expands and fills with semen Contractions of vas deferens Contractions of prostate gland Contractions of seminal vesicle Sphincter contracts Contractions of epididymis First stage Sphincter remains contracted Contractions of muscles around base of penis Sphincter relaxes Contractions of urethra Second stage Semen expelled Figure 27.3C

12. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings A negative feedback system of hormones –Controls sperm production Stimuli from other areas in the brain Hypothalamus Releasing hormone Anterior pituitary Negative feedback FSH LH Androgen production Sperm production Testis Figure 27.3D

13. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.5 Hormones synchronize cyclic changes in the ovary and uterus ovarian cycle includes –Changes in ovary –occur ~ every 28 days menstrual cycle –changes occur in uterus

14. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings An Overview of the Ovarian and Menstrual Cycles Events in the menstrual cycle –synchronized with ovarian cycle, which occurs about every 28 days

15. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Uterine bleeding, called menstruation –Includes breakdown of endometrial lining –Usually persists for 3–5 days After menstruation –endometrium, lining of uterus, regrows

16. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Five hormones –Synchronize events in ovarian cycle Table 27.5

17. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Hormonal Events Before Ovulation Approximately every 28 days –hypothalamus signals anterior pituitary to secrete FSH and LH FSH and LH –Trigger growth of a follicle

18. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings As the follicle grows, it secretes estrogen –causes a burst in FSH and LH levels, leading to ovulation

19. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings development of an ovarian follicle Corpus luteum Degenerating corpus luteum Start: Primary oocyte within follicle Growing follicles Mature follicle Ovary Ruptured follicle Ovulation Secondary oocyte Figure 27.4C

20. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Hormonal Events at Ovulation and After After ovulation –follicle becomes the corpus luteum secretes both estrogen & progesterone –exert negative feedback on hypothalamus and pituitary, –causing a decline in FSH and LH levels

21. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings As FSH and LH levels drop –hypothalamus can once again stimulate pituitary to secrete more FSH and LH, and a new cycle begins

22. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Control of the Menstrual Cycle –directly controlled by estrogen and progesterone

23. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings If fertilization of an egg occurs –hormone from embryo maintains uterine lining and prevents menstruation

24. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The ovarian and menstrual cycles A B Control by hypothalamus Hypothalamus Releasing hormone Anterior pituitary Inhibited by combination of estrogen and progesterone Stimulated by high levels of estrogen FSHLH Pituitary hormones in blood LH FSH LH LH peak triggers ovulation and corpus luteum formation Ovarian cycle Growing follicle Pre-ovulatory phase Mature follicle Ovulation Corpus luteum Post-ovulatory phase Degenerating corpus luteum Estrogen Progesterone and estrogen Ovarian hormones in blood Estrogen Progesterone Estrogen Progesterone and estrogen C D E Menstrual cycle Endometrium 051014 15202528 Days Menstruation Figure 27.5 1 4 6 2 5 3 7 8

25. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 27.19 Reproductive technology increases our reproductive options New techniques –Can provide help to infertile couples Figure 27.19

26. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Some of these methods –Raise important ethical and legal questions

27. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings

28. ASEXUAL AND SEXUAL REPRODUCTION 27.1 Sexual and asexual reproduction are both common among animals In asexual reproduction –One parent produces genetically identical offspring

29. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Modes of asexual reproduction include –Budding, fission, or fragmentation/regeneration LM 25  Figure 27.1A, B

30. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Asexual reproduction –Enables an individual to produce many offspring rapidly

31. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Sexual reproduction involves the fusion of gametes from two parents –Resulting in genetic variation among offspring “Head” Intestine Ovary Eggs LM 210  Figure 27.1C

32. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Some animals exhibit hermaphroditism –In which each individual has both female and male reproductive systems Figure 27.1D

33. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Reproduction in some animals is accomplished through external fertilization –In which the parents release their gametes into the environment where fertilization occurs Eggs Figure 27.1E

34. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Sexual reproduction –May enhance reproductive success in changing environments

35. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.4 The formation of sperm and ova requires meiosis Spermatogenesis, the formation of sperm cells –Takes about 65–75 days in the human male

36. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Primary spermatocytes, which are diploid, are made continuously in the testes –And undergo meiosis to produce haploid sperm Primary spermatocyte Differentiation and onset of Meiosis I Meiosis I completed Meiosis II Differentiation (in prophase of Meiosis I) Secondary spermatocyte (haploid; double chromatids) Developing sperm cells (haploid; single chromatids) Sperm cells (haploid) Center of seminiferous tubule n nnn n nnn nn 2n2n 2n2n Testis Scrotum Penis Epididymis Testis Seminiferous tubule Cross section of seminiferous tubule Diploid cell Figure 27.4A

37. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Each month one primary oocyte –Matures to form a secondary oocyte, which can be fertilized –Completes meiosis and becomes a haploid ovum Diploid cell In embryo 2n2n Differentiation and onset of Meiosis I Primary oocyte (arrested in prophase of Meiosis I) 2n2nPresent at birth Completion of Meiosis I and onset of Meiosis II Secondary oocyte (arrested at meta- phase of Meiosis II; released from ovary) n n Entry of sperm triggers completion of Meiosis II Ovum (haploid) n n Second polar body First polar body Figure 27.4B

38. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.6 The human sexual response occurs in four phases The excitement phase –Prepares the sexual organs for coitus The plateau phase –Is marked by increases in breathing and heart rate

39. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Orgasm follows –Characterized by rhythmic contractions of the reproductive structures The resolution phase –Completes the cycle and reverses the previous responses

40. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 27.7 Sexual activity can transmit disease Sexual intercourse –Carries the risk of exposure to sexually transmitted diseases (STDs)

41. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings STDs common in the United States Table 27.7

42. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings CONNECTION 27.8 Contraception can prevent unwanted pregnancy Contraception –Is the deliberate prevention of pregnancy Table 27.8

43. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Contraception can be accomplished –Through various methods Skin patch Diaphragm Spermicide Condom Birth control pills Figure 27.8

44. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings PRINCIPLES OF EMBRYONIC DEVELOPMENT 27.9 Fertilization results in a zygote and triggers embryonic development Embryonic development begins with fertilization –The union of sperm and egg to form a diploid zygote

45. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The Properties of Sperm Cells Only one sperm –Fertilizes an egg Colorized SEM 500  Figure 27.9A

46. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings During fertilization –A sperm releases enzymes from the acrosome that pierce the egg’s coat Plasma membrane Middle piece Head Neck Mitochondrion (spiral shape) Nucleus Acrosome Tail Figure 27.9B

47. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The Process of Fertilization Sperm surface proteins bind to egg receptor proteins –Sperm and egg plasma membranes fuse, and the two nuclei unite

48. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Changes in the egg membrane –Prevent entry of additional sperm The fertilized egg (zygote) –Develops into an embryo

49. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Figure 27.9C The process of fertilization Nucleus Acrosome Sperm Plasma membrane Sperm head Acrosomal enzymes Jelly coat Vitelline layer Plasma membrane Receptor protein molecules Sperm nucleus Cytoplasm Egg nucleus Egg cell Zygote nucleus The sperm approaches the egg 1 Proteins on the sperm head bind to egg receptors 3 The plasma membranes of sperm and egg fuse 4 The sperm nucleus enters the egg cytoplasm 5 A fertilization envelope forms 6 The sperm’s acrosomal enzymes digest the egg’s jelly coat 2 The nuclei of sperm and egg fuse 7

50. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.10 Cleavage produces a ball of cells from the zygote Cleavage is a rapid series of cell divisions –That results in a blastula, a ball of cells Zygote 2 cells 4 cells 8 cells Many cells (solid ball) Blastula (hollow ball) Cross section of blastula Blastocoel Figure 27.10

51. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.11 Gastrulation produces a three-layered embryo In gastrulation –Cells migrate inward and form a rudimentary digestive cavity The resulting gastrula –Has three layers of cells

52. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Development of the frog gastrula Figure 27.11 Animal pole Blastocoel Vegetal pole Blastula The blastula 1 1 Gastrulation Blastopore forming Blastopore formation 2 2 Archenteron Cell migration to form layers 3 Blastocoel shrinking 3 Archenteron Ectoderm Mesoderm Endoderm Yolk plug Gastrula Completion of gastrulation 4 4

53. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.12 Organs start to form after gastrulation After gastrulation –The three embryonic tissue layers give rise to specific organ systems Neural fold Neural plate Notochord Ectoderm Mesoderm Endoderm Archenteron Neural folds 15  Figure 27.12A

54. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings A structure known as the neural plate –Forms the neural tube, which will become the spinal cord Neural fold Neural plate Outer layer of ectoderm Neural tube Figure 27.12B

55. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings After neural tube formation –The somites and the coelom form Neural tube Somite Notochord Coelom Archenteron (digestive cavity) Somites Tail bud Eye SEM 15  Figure 27.12C

56. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings During one stage of frog development, a tadpole forms –Which eventually develops into an adult frog Figure 27.12D

57. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The three embryonic tissue layers –Develop into a number of different organs and tissues in an adult Table 27.12

58. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.13 Changes in cell shape, cell migration, and programmed cell death give form to the developing animal Cells of the ectoderm –Fold inward during neural tube formation Ectoderm Figure 27.13A

59. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Programmed cell death, or apoptosis –Is a key developmental process in which cells die Figure 27.13B Apoptosis Dead cell engulfed and digested by adjacent cell

60. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.14 Embryonic induction initiates organ formation In a process called induction –Adjacent cells and cell layers influence each other’s differentiation via chemical signals

61. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Future brain Optic vesicle Lens ectoderm Optic stalk Optic cup Cornea Lens Future retina Figure 27.14 Induction during eye development 1234

62. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.15 Pattern formation organizes the animal body Pattern formation –Is the emergence of the parts of a structure in their correct relative positions

63. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings –Involves the response of genes to spatial variations of chemicals in the embryo Anterior Bird embryo Ventral Limb bud Distal Proximal Posterior Dorsal Limb bud develops Normal wing Figure 27.15A

64. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Experimental evidence has revealed –That vertebrate limbs have zones of cells that provide positional information to other cells Donor limb bud Donor cells Graft of cells from pattern- forming zone Host limb bud Graft Host pattern- forming zone Host limb bud develops Wing with duplication Figure 27.15B

65. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings HUMAN DEVELOPMENT 27.16 The embryo and placenta take shape during the first month of pregnancy Pregnancy, or gestation –Is the carrying of developing young within the female reproductive tract

66. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings An Overview of Developmental Events Human development –Begins with fertilization in the oviduct Cleavage starts Fertilization of ovum Oviduct Secondary oocyte Ovulation Ovary Blastocyst (implanted) Endometrium Uterus Figure 27.16A

67. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Cleavage produces a blastocyst –Whose inner cell mass becomes the embryo Endometrium Inner cell mass Cavity Trophoblast Figure 27.16B

68. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The blastocyst’s outer layer, the trophoblast –Implants in the uterine wall Endometrium Future embryo Future yolk sac Blood vessel (maternal) Multiplying cells of trophoblast Trophoblast Uterine cavity Figure 27.16C

69. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Meanwhile, the four extraembryonic membranes develop –The amnion, the chorion, the yolk sac, and the allantois Amniotic cavity Amnion Mesoderm cells Chorion Yolk sac Chorion Amnion Allantois Yolk sac Chorionic villi Embryo: Ectoderm Mesoderm Endoderm Figure 27.16D, E

70. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Roles of the Extraembryonic Membranes About a month after conception –The extraembryonic membranes are fully formed Mother’s blood vessels Allantois Yolk sac Placenta Amniotic cavity Amnion Embryo Chorion Chorionic villi Figure 27.16F

71. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The embryo floats in a fluid-filled amniotic cavity –Surrounded by the amnion The chorion and mesoderm cells from the yolk sac –Form the embryo’s part of the placenta

72. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The allantois –Forms part of the umbilical cord

73. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The Placenta The placenta’s chorionic villi –Absorb food and oxygen from the mother’s blood to nourish the embryo

74. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.17 Human development from conception to birth is divided into three trimesters Human development is divided into three trimesters –Each about three months in length

75. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings The First Trimester The most rapid changes –Occur during the first trimester Figure 27.17A

76. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings By 9 weeks –The embryo is called a fetus Figure 27.17B

77. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Second Trimester The second trimester –Involves an increase in size and general refinement of the human features Figure 27.17C

78. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings At 20 weeks –The fetus is about 19 centimeters long, and weighs half a kilogram Figure 27.17D

79. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Third Trimester The third trimester –Is a time of rapid growth, which ends in birth Figure 27.17E

80. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings 27.18 Childbirth is hormonally induced and occurs in three stages The birth of a child –Is brought about by a series of strong, rhythmic contractions of the uterus, called labor

81. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Estrogen makes the uterus more sensitive to oxytocin –Which acts with prostaglandins to initiate labor EstrogenOxytocin from ovaries from fetus and pituitary Induces oxytocin receptors on uterus Stimulates uterus to contract Stimulates placenta to make Prostaglandins Stimulate more contractions of uterus Positive feedback Figure 27.18A

82. Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings Placenta Umbilical cord Uterus Cervix Uterus Placenta (detaching) Umbilical cord Figure 27.18B Labor occurs in three stages –Dilation, expulsion, and delivery of the placenta Dilation of the cervix 1 Expulsion: delivery of the infant2 Delivery of the placenta 3