1. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece Lectures by Chris Romero Chapter 46 Animal Reproduction

2. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Overview: Doubling Up for Sexual Reproduction The two earthworms in this picture are mating Each worm produces both sperm and eggs, which will fertilize – And in a few weeks, new worms will hatch Figure 46.1

3. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A population transcends finite life spans – Only by reproduction

4. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 46.1: Both asexual and sexual reproduction occur in the animal kingdom Asexual reproduction is the creation of new individuals – Whose genes all come from one parent

5. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sexual reproduction is the creation of offspring – By the fusion of male and female gametes to form a zygote The female gamete is the egg The male gamete is the sperm

6. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mechanisms of Asexual Reproduction Many invertebrates reproduce asexually by fission – The separation of a parent into two or more individuals of approximately the same size Figure 46.2

7. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Also common in invertebrates is budding – In which two new individuals arise from outgrowths of existing ones Another type of asexual reproduction is fragmentation, which – Is the breaking of the body into several pieces, some or all of which develop into complete adults – Must be accompanied by regeneration, the regrowth of lost body parts

8. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Reproductive Cycles and Patterns Most animals exhibit cycles in reproductive activity – Often related to changing seasons Reproductive cycles – Are controlled by hormones and environmental cues

9. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Animals may reproduce exclusively asexually or sexually – Or they may alternate between the two Some animals reproduce by parthenogenesis – A process in which an egg develops without being fertilized

10. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Among vertebrates, several genera of fishes, amphibians, and lizards, including whiptail lizards – Reproduce exclusively by a complex form of parthenogenesis Figure 46.3a, b Time Ovary size Hormones Behavior Ovulation Progesterone Estrogen Female- like Male- like Female- like Male- like (a) Both lizards in this photograph are C. uniparens females. The one on top is playing the role of a male. Every two or three weeks during the breeding season, individuals switch sex roles. (b) The sexual behavior of C. uniparens is correlated with the cycle of ovulation mediated by sex hormones. As blood levels of estrogen rise, the ovaries grow, and the lizard behaves like a female. After ovulation, the estrogen level drops abruptly, and the progesterone level rises; these hormone levels correlate with male behavior.

11. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Sexual reproduction presents a special problem for certain organisms – That seldom encounter a mate One solution to this problem is hermaphroditism – In which each individual has both male and female reproductive systems

12. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Another remarkable reproductive pattern is sequential hermaphroditism – In which an individual reverses its sex during its lifetime Figure 46.4

13. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 46.2: Fertilization depends on mechanisms that help sperm meet eggs of the same species The mechanisms of fertilization, the union of egg and sperm – Play an important part in sexual reproduction

14. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Some species have external fertilization, in which – Eggs shed by the female are fertilized by sperm in the external environment Figure 46.5 Eggs

15. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Other species have internal fertilization, in which – Sperm are deposited in or near the female reproductive tract, and fertilization occurs within the tract

16. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In either situation, fertilization requires critical timing – Often mediated by environmental cues, pheromones, and/or courtship behavior Internal fertilization – Requires important behavioral interactions between male and female animals – Requires compatible copulatory organs

17. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ensuring the Survival of Offspring All species produce more offspring than the environment can handle – But the proportion that survives is quite small

18. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The embryos of many terrestrial animals – Develop in eggs that can withstand harsh environments Instead of secreting a shell around the embryo – Many animals retain the embryo, which develops inside the female

19. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Many different types of animals – Exhibit parental care to ensure survival of offspring Figure 46.6

20. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Gamete Production and Delivery To reproduce sexually – Animals must have systems that produce gametes

21. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The least complex systems – Do not even contain distinct gonads, the organs that produce gametes in most animals

22. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The most complex reproductive systems – Contain many sets of accessory tubes and glands that carry, nourish, and protect the gametes and the developing embryos

23. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Many animals with relatively simple body plans – Possess highly complex reproductive systems Figure 46.7 Male organs: Female organs: Genital pore (Excretory pore) Seminal receptacle (Digestive tract) Testis 1 Vas efferens 2 Sperm duct (vas deferens) 3 Seminal vesicle 4 Ovary 1 Oviduct 2 Yolk duct Yolk gland 3Uterus

24. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Most insects – Have separate sexes with complex reproductive systems Figure 46.8a, b (a) Male honeybee. Sperm form in the testes, pass through the sperm duct (vas deferens), and are stored in the seminal vesicle. The male ejaculates sperm along with fluid from the accessory glands. (Males of some species of insects and other arthropods have appendages called claspers that grasp the female during copulation.) (b) Female honeybee. Eggs develop in the ovaries and then pass through the oviducts and into the vagina. A pair of accessory glands (only one is shown) add protective secretions to the eggs in the vagina. After mating, sperm are stored in the spermatheca, a sac connected to the vagina by a short duct. Testis 1 Accessory gland 3 Seminal vesicle Vas deferens 2 Penis 5 Ejaculatory duct 4 Accessory gland Spermatheca Ovary 1 Vagina 3 Oviduct

25. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 46.3: Reproductive organs produce and transport gametes: focus on humans

26. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Female Reproductive Anatomy The female external reproductive structures include – The clitoris – Two sets of labia

27. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The internal organs are a pair of gonads – And a system of ducts and chambers that carry gametes and house the embryo and fetus

28. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Reproductive anatomy of the human female Prepuce (Rectum) Cervix Vagina Bartholin’s gland Vaginal opening Ovary Oviduct Labia majora Labia minora (Urinary bladder) (Pubic bone) Uterus Urethra Shaft Glans Clitoris Figure 46.9

29. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Vagina Uterus Cervix Ovaries Oviduct Uterine wall Endometrium Follicles Corpus luteum

30. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ovaries The female gonads, the ovaries – Lie in the abdominal cavity

31. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Each ovary – Is enclosed in a tough protective capsule and contains many follicles A follicle – Consists of one egg cell surrounded by one or more layers of follicle cells

32. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The process of ovulation – Expels an egg cell from the follicle The remaining follicular tissue then grows within the ovary – To form a solid mass called the corpus luteum, which secretes hormones, depending on whether or not pregnancy occurs

33. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Oviducts and Uterus The egg cell is released into the abdominal cavity – Near the opening of the oviduct, or fallopian tube Cilia in the tube – Convey the egg to the uterus

34. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Vagina and Vulva The vagina is a thin-walled chamber – That is the repository for sperm during copulation – That serves as the birth canal through which a baby is born

35. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The vagina opens to the outside at the vulva – Which includes the hymen, vestibule, labia minora, labia majora, and clitoris

36. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mammary Glands The mammary glands are not part of the reproductive system – But are important to mammalian reproduction Within the glands – Small sacs of epithelial tissue secrete milk

37. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Male Reproductive Anatomy In most mammalian species – The male’s external reproductive organs are the scrotum and penis The internal organs – Consist of the gonads, which produce sperm and hormones, and accessory glands

38. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Reproductive anatomy of the human male Figure 46.10 Erectile tissue of penis Prostate gland (Urinary bladder) Bulbourethral gland Vas deferens Epididymis Testis Seminal vesicle (behind bladder) Urethra Scrotum Glans penis

39. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Seminal vesicle (Rectum) Vas deferens Ejaculatory duct Prostate gland Bulbourethral gland (Urinary bladder) (Pubic bone) Erectile tissue of penis Urethra Glans penis Prepuce Vas deferens Epididymis Testis Scrotum

40. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Testes The male gonads, or testes – Consist of many highly coiled tubes surrounded by several layers of connective tissue The tubes are seminiferous tubules – Where sperm form

41. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Production of normal sperm – Cannot occur at the body temperatures of most mammals The testes of humans and many mammals – Are held outside the abdominal cavity in the scrotum, where the temperature is lower than in the abdominal cavity

42. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ducts From the seminiferous tubules of a testis – The sperm pass into the coiled tubules of the epididymis During ejaculation – Sperm are propelled through the muscular vas deferens, the ejaculatory duct, and exit the penis through the urethra

43. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Glands Three sets of accessory glands – Add secretions to the semen, the fluid that is ejaculated A pair of seminal vesicles – Contributes about 60% of the total volume of semen

44. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The prostate gland – Secretes its products directly into the urethra through several small ducts The bulbourethral gland – Secretes a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra

45. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Semen in the Female Reproductive Tract Once in the female reproductive tract – A number of processes, including contractions of the uterus, help move the sperm up the uterus

46. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Penis The human penis – Is composed of three cylinders of spongy erectile tissue During sexual arousal – The erectile tissue fills with blood from the arteries, causing an erection

47. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Human Sexual Response Two types of physiological reactions predominate in both sexes – Vasocongestion, the filling of tissue with blood – Myotonia, increased muscle tension

48. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The sexual response cycle can be divided into four phases – Excitement, plateau, orgasm, and resolution

49. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 46.4: In humans and other mammals, a complex interplay of hormones regulates gametogenesis The process of gametogenesis – Is based on meiosis, but differs in females and males

50. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Ovary Primary germ cell in embryo Differentiation Oogonium in ovary Mitotic division Primary oocyte, arrested in prophase of meiosis I (present at birth) Completion of meiosis I and onset of meiosis II Primary oocyte within follicle Secondary oocyte, arrested at meta- phase of meiosis II First polar body Ovulation Entry of sperm triggers completion of meiosis II Ovum Growing follicle Mature follicle Ruptured follicle Ovulated secondary oocyte Corpus luteum Degenerating corpus luteum 2n2n 2n2n n n n n Figure 46.11 Oogenesis is the development of mature ova

51. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Spermatogenesis is the production of mature sperm Epididymis Seminiferous tubule Testis Cross section of seminiferous tubule Sertoli cell nucleus Lumen of Seminiferous tubule Spermatogonium Primary spermatocyte (in prophase of meiosis I) Secondary spermatocyte Early spermatids Spermatids (at two stages of differentiation) Differentiation (Sertoli cells provide nutrients) Meiosis II Meiosis I completed Mitotic division, producing large numbers of spermatogonia Sperm cells Acrosome Nucleus Mitochondria Neck Tail Plasma membrane HeadMidpiece 2n2n 2n2n n n n nnn n n n n Figure 46.12 Differentiation and onset of meiosis I

52. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Oogenesis differs from spermatogenesis – In three major ways

53. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings First, during the meiotic divisions of oogenesis – Cytokinesis is unequal, with almost all the cytoplasm monopolized by a single daughter cell, the secondary oocyte

54. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Second, sperm are produced continuously throughout a male’s life – Which is not the case in oogenesis Third, oogenesis has long “resting” periods – While spermatogenesis produces sperm in uninterrupted sequence

55. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Reproductive Cycles of Females In females – The secretion of hormones and the reproductive events they regulate are cyclic

56. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Menstrual Versus Estrous Cycles Two different types of cycles occur in females

57. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Humans and other primates have menstrual cycles – While other mammals have estrous cycles In both cases ovulation occurs at a time in the cycle – After the endometrium has started to thicken in preparation for implantation

58. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings In menstrual cycles – The endometrium is shed from the uterus in a bleeding called menstruation – Sexual receptivity is not limited to a specific timeframe In estrous cycles – The endometrium is reabsorbed by the uterus – Sexual receptivity is limited to a “heat” period

59. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Human Female Reproductive Cycle: A Closer Look The female reproductive cycle – Is one integrated cycle involving two organs, the uterus and ovaries

60. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Cyclic secretion of GnRH from the hypothalamus – And of FSH and LH from the anterior pituitary orchestrates the female reproductive cycle Five kinds of hormones – Participate in an elaborate scheme involving both positive and negative feedback

61. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The reproductive cycle of the human female Figure 46.13a–e Control by hypothalamus Inhibited by combination of estrogen and progesterone Stimulated by high levels of estrogen Inhibited by low levels of estrogen Hypothalamus Anterior pituitary GnRH FSH LH Pituitary gonadotropins in blood LH FSH FSH and LH stimulate follicle to grow LH surge triggers ovulation Ovarian cycle Growing follicle Mature follicle Corpus luteum Degenerating corpus luteum Estrogen secreted by growing follicle in increasing amounts Progesterone and estrogen secreted by corpus luteum Follicular phase Luteal phaseOvulation Ovarian hormones in blood Peak causes LH surge Estrogen Progesterone Estrogen level very low Progesterone and estro- gen promote thickening of endometrium Uterine (menstrual) cycle Endometrium Menstrual flow phase Proliferative phase Secretory phase 0 5 10 1415 20 2528 Days 1 (a) (b) (c) (d) (e) 3 6 7 8 4 5 2 10 9

62. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Ovarian Cycle In the ovarian cycle – Hormones stimulate follicle growth, which results in ovulation Following ovulation – The follicular tissue left behind transforms into the corpus luteum

63. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Uterine (Menstrual) Cycle Cycle after cycle – The maturation and release of egg cells from the ovary are integrated with changes in the uterus If an embryo has not implanted in the endometrium by the end of the secretory phase – A new menstrual flow commences

64. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Menopause After about 450 cycles, human females undergo menopause – The cessation of ovulation and menstruation

65. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Hormonal Control of the Male Reproductive System Testosterone and other androgens – Are directly responsible for the primary and secondary sex characteristics of the male

66. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Androgen secretion and sperm production – Are both controlled by hypothalamic and pituitary hormones Stimuli from other areas in the brain Hypothalamus GnRH from the hypothalamus reg- ulates FSH and LH release from the anterior pituitary. FSH acts on the Sertoli cells of the seminiferous tubules, promoting spermatogenesis. LH stimulates the Leydig cells to make testosterone, which in turn stimulates sperm production. Anterior pituitary Negative feedback Leydig cells make testosterone Primary and secondary sex characteristics Sertoli cells Spermatogenesis Testis Figure 46.14

67. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Concept 46.5: In humans and other placental mammals, an embryo grows into a newborn in the mother’s uterus

68. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Conception, Embryonic Development, and Birth In humans and most other placental mammals – Pregnancy, or gestation, is the condition of carrying one or more embryos in the uterus

69. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Fertilization of an egg by a sperm, conception – Occurs in the oviduct Figure 46.15a, b Ovary Uterus Endometrium From ovulation to implantation Endometrium Inner cell mass Cavity Blastocyst Trophoblast (a) Implantation of blastocyst(b) Ovulation releases a secondary oocyte, which enters the oviduct. 1 Fertilization occurs. A sperm enters the oocyte; meiosis of the oocyte finishes; and the nuclei of the ovum and sperm fuse, producing a zygote. 2 Cleavage (cell division) begins in the oviduct as the embryo is moved toward the uterus by peristalsis and the movements of cilia. 3 Cleavage continues. By the time the embryo reaches the uterus, it is a ball of cells. It floats in the uterus for several days, nourished by endometrial secretions. It becomes a blastocyst. 4 The blastocyst implants in the endometrium about 7 days after conception. 5

70. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings After fertilization – The zygote undergoes cleavage and develops into a blastocyst before implantation in the endometrium

71. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings First Trimester Human gestation – Can be divided into three trimesters of about three months each The first trimester – Is the time of most radical change for both the mother and the embryo

72. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings During its first 2 to 4 weeks of development – The embryo obtains nutrients directly from the endometrium Meanwhile, the outer layer of the blastocyst – Mingles with the endometrium and eventually forms the placenta

73. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Blood from the embryo – Travels to the placenta through arteries of the umbilical cord and returns via the umbilical vein Placenta Umbilical cord Chorionic villus containing fetal capillaries Maternal blood pools Uterus Fetal arteriole Fetal venule Umbilical cord Maternal portion of placenta Fetal portion of placenta (chorion) Umbilical arteries Umbilical vein Maternal arteries Maternal veins Figure 46.16

74. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The first trimester is the main period of organogenesis – The development of the body organs Figure 46.17a–c (a) 5 weeks. Limb buds, eyes, the heart, the liver, and rudiments of all other organs have started to develop in the embryo, which is only about 1 cm long. (b) 14 weeks. Growth and development of the offspring, now called a fetus, continue during the second trimester. This fetus is about 6 cm long. (c) 20 weeks. By the end of the second trimester (at 24 weeks), the fetus grows to about 30 cm in length.

75. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Second Trimester During the second trimester – The fetus grows and is very active – The mother may feel fetal movements – The uterus grows enough for the pregnancy to become obvious

76. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Third Trimester During the third trimester – The fetus continues to grow and fills the available space within the embryonic membranes

77. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings A complex interplay of local regulators and hormones – Induces and regulates labor, the process by which childbirth occurs EstrogenOxytocin from ovaries from fetus and mother's posterior pituitary Induces oxytocin receptors on uterus Stimulates uterus to contract Stimulates placenta to make Prostaglandins Stimulate more contractions of uterus Positive feedback Figure 46.18

78. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Birth, or parturition – Is brought about by a series of strong, rhythmic uterine contractions

79. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The process of labor has three stages Figure 46.19 Placenta Umbilical cord Uterus Cervix Dilation of the cervix Expulsion: delivery of the infant Uterus Placenta (detaching) Umbilical cord Delivery of the placenta 1 2 3

80. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings The Mother’s Immune Tolerance of the Embryo and Fetus A woman’s acceptance of her “foreign” offspring – Is not fully understood – May be due to the suppression of the immune response in her uterus

81. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Contraception and Abortion Contraception, the deliberate prevention of pregnancy – Can be achieved in a number of ways

82. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Some contraceptive methods – Prevent the release of mature eggs and sperm from gonads – Prevent fertilization by keeping sperm and egg apart – Prevent implantation of an embryo

83. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Mechanisms of some contraceptive methods Figure 46.20 Male Female Method Event Method Production of viable sperm Production of viable oocytes Vasectomy Combination birth control pill (or injection, patch, or vaginal ring) Sperm transport down male duct system Ovulation Abstinence Condom Coitus interruptus (very high failure rate) Sperm deposited in vagina Capture of the oocyte by the oviduct Abstinence Tubal ligation Spermicides; diaphragm; cervical cap; progestin alone (minipill, implant, or injection) Sperm movement through female reproductive tract Transport of oocyte in oviduct Meeting of sperm and oocyte in oviduct Morning-after pill (MAP) Union of sperm and egg Implantation of blastocyst in properly prepared endometrium Birth Progestin alone

84. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Modern Reproductive Technology Recent scientific and technological advances – Have made it possible to deal with many reproductive problems

85. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Amniocentesis and chorionic villus sampling – Are invasive techniques in which amniotic fluid or fetal cells are obtained for genetic analysis

86. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Noninvasive procedures – Usually use ultrasound imaging to detect fetal condition Figure 46.21 Head Body Head Body

87. Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings Modern technology – Can help infertile couples by in vitro fertilization