1. Human Reproduction and Development
Fertilization
Pregnancy
Development
Birth

2. Human Reproduction and Development
Sperm

3. Human Reproduction and Development

4. 3 Steps of Fertilization
Capacitating
Acidic environment of the female reproductive tract causes small pores to open in the acrosome (“enzyme-loaded” head) of the sperm

5. 3 Steps of Fertilization
Acrosome

6. 3 Steps of Fertilization
Capacitating
Acidic environment of the female reproductive tract causes small pores to open in the acrosome (“enzyme-loaded” head) of the sperm
Acrosomal reaction
Enzymes released from acrosome digest the outer membrane surrounding the egg cell

7. 3 Steps of Fertilization
A single sperm cell fuses with the plasma membrane of ovum
Head passes into the cytoplasm
Electrochemical reaction in egg
Makes membrane impermeable to other sperm

8. Fertilization
Fertilization must occur within a very short window of opportunity.
Egg is only fertile for hours
Sperm can survive up to 5 days in the body
Sex (copulation) must occur no more than 5 days before or 1 day after ovulation

9. Pregnancy If pregnancy is established, menstruation does not occur.
Fertilized egg is called a zygote.
Once cell division brings the total cell count to around 8, it is called a blastocyst.
Takes 3-5 days for blastocyst to travel through oviduct to uterus.
Blastocyst must implant into endometrium
Occurs 2-4 days after reaching the uterus

10. Fertilization
If pregnancy is established, menstruation does not occur.
Fertilized egg is called a zygote.
Once cell division brings the total cell count to around 8, it is called a blastocyst.
Takes 3-5 days for blastocyst to travel through oviduct to uterus.
Blastocyst must implant into endometrium
Occurs 2-4 days after reaching the uterus

11. Fertilization
If pregnancy is established, menstruation does not occur.
Fertilized egg is called a zygote.
Once cell division brings the total cell count to around 8, it is called a blastocyst.
Takes 3-5 days for blastocyst to travel through oviduct to uterus.
Blastocyst must implant into endometrium
Occurs 2-4 days after reaching the uterus

12. Fertilization
If pregnancy is established, menstruation does not occur.
Fertilized egg is called a zygote.
Once cell division brings the total cell count to around 8, it is called a blastocyst.
Takes 3-5 days for blastocyst to travel through oviduct to uterus.
Blastocyst must implant into endometrium
Occurs 2-4 days after reaching the uterus

13. Pregnancy
During implantation, the blastocyst produces a hormone called HCG
Human chorionic gonadotropin
Prevents degeneration of corpus luteum
Stimulates corpus luteum to increase progesterone secretion
Maintains uterine lining
Prevents contractions
Pregnancy test detects HCG in the urine of women.
“Turns the stick blue”

14. Pregnancy
Tissue grows out from the embryo and mingles with endometrium to form placenta
A disc-shaped organ
Size of dinner plate
Weighs less than 1 kg.
Contains maternal & fetal blood vessels
NO mixing of maternal and fetal blood!!
Diffusion of gasses, nutrients, & wastes
Continues production of HCG, estrogen, progesterone
Maintains endometrium
Corpus luteum not needed – dissolves

15. Pregnancy
Progesterone & estrogen have a negative feedback effect on the hypothalamus
No secretion of FSH
No secretion of LH
No new follicles mature
Embryo remains firmly attached to placenta by umbilical cord.

16. Pregnancy Umbilical cord Contains: 2 fetal arteries Fetus to placenta
One fetal vein
Placenta to fetus

17. Pregnancy

19. Childbirth Also called parturition 38 – 42 weeks from conception
Average = 40 weeks
Three stages of childbirth
Labour
Delivery
Afterbirth

20. Childbirth Labour Involuntary Rhythmic contractions of the uterus
Causes cervix to open
Diameter = 10 cm
Delivery
Involuntary uterine contractions
Conscious abdominal contractions
Mother forces baby out through cervix and vagina

21. Childbirth Afterbirth Immediately after delivery
Blood vessels in placenta contract
Placenta separates from uterine wall
Expelled by muscle contractions

22. Childbirth Why?? Nobody totally knows.
Baby plays some role in the timing.
Progesterone decreases
Allows uterus to contract
Oxytocin from posterior pituitary
Stimulates stronger uterine contractions
Relaxin
produced by placenta
Causes ligaments of pelvis to loosen
Larger passageway for baby

23. Lactation
During pregnancy, high levels of estrogen and progesterone prepare the breasts for milk production
Each breast has about 20 milk glands
Connect to the nipple by ducts
Breast enlarges during pregnancy in preparation for lactation
Expulsion of the placenta causes the mother's pituitary to secrete prolactin,
Initiates lactation

24. Lactation Prolactin inhibits the release of LH
menstrual cycle is suppressed in nursing mothers
The high estrogen and progesterone levels during pregnancy are thought to inhibit release of prolactin

25. Lactation The first fluid formed by the mammary glands is colostrum,
Thick
contains lactose and milk proteins,
lacks fat
after a few days, milk is produced
Oxytocin is released from hypothalamus when infant suckles
Causes milk to be released from mammary glands

26. Fetal Development A blastocyst embeds in the uterine wall
Consists of cells of the future embryo
Surrounded by a sphere of cells
Embryonic membrane (extra-embryonic membrane)
Support the developing embryo

27. Fetal Development Amnion Innermost embryonic membrane Next to baby
Fluid-filled sac that cushions the baby

28. Fetal Development Chorion Outermost membrane Part of the placenta
Secretes HCG

29. Fetal Development Umbilical cord Connection between mother and baby
Belly-button to placenta
Carries baby’s blood to and from placenta

30. Embryonic Development
Placenta (review)
A disc-shaped organ
Size of dinner plate
Contains maternal & fetal blood vessels
NO mixing of maternal and fetal blood!!
Diffusion of gasses, nutrients, & wastes
Continues production of HCG, estrogen, progesterone

32. Embryonic Development
A blastocyst undergoes gastrulation
Series of cell movements and shape changes
Produces an embryo with 3 cellular layers
Ectoderm
Outer layer of cells
Will become skin and nervous system
Mesoderm
Middle layer of cells
Skeleton, muscles gonads, kidneys, circulatory system
Endoderm
Inner layer of cells
Liver, pancreas, lungs, lining of digestive tract

33. Gastrulation

34. Human Gestation 1st Trimester
From fertilization to end of 3rd month (0 – 13 weeks)
Zygote begins cell division as it moves down oviduct
Becomes blastocyst and implants in uterus

35. Human Gestation 1st Trimester Development of body organs
Heart starts beating by week 4
Week 7, testosterone begins to be secreted if a Y-chromosome is present
This testosterone causes development of testes.

36. Human Gestation 1st Trimester
By week-8 all major structures of the adult are present (in basic form)
Embryo is now called a fetus
Embryo is most sensitive during first trimester
Due to rapid development
Sensitive to radiation and drugs

37. Gastrulation

38. Gastrulation
6 weeks

39. 7 weeks
Gastrulation

40. Gastrulation
8 Weeks

41. 8 weeks

42. 10 Weeks

43. 11 Weeks

44. 11 Weeks

45. 14 Weeks

46. Human Gestation 2nd Trimester Fetus grows rapidly To about 30 cm
Quite active
Hair begins to develop
Cartilage of skeleton is replaced by bone

47. 18 weeks
Gastrulation

48. The Hand Picture
May 2, 2000
USA Today

49. An Amazing Story -- Aug.19, 1999
Samuel Armas' tiny hand grips Dr. Joseph P. Bruner's finger just as Bruner finishes returning him to his mother's womb.
Bruner, director of fetal diagnosis and treatment at Vanderbilt University Medical Center (Nashville), was performing a cutting-edge procedure on the 21-week-old fetus.
The procedure on Samuel took about an hour.

50. An Amazing Story -- Aug.19, 1999
Bruner and Samuel's parents hope the surgery will alleviate the effects of spina bifida, a disabling birth defect in one or two of every 1,000 babies born.
Because fetuses undergoing this procedure are so young -- Samuel could not survive outside his mother's womb -- this kind of surgery is gaining attention nationwide from the medical community and the media.

51. An Amazing Story -- Aug.19, 1999
During the procedure, surgeons remove the uterus from the mother, drain the amniotic fluid, perform surgery on the tiny fetus, replace everything and put the entire package back inside the mother.
Dr. Bruner said regarding the picture, "The baby did not reach out," Bruner says. "The baby was anesthetized. The baby was not aware of what was going on."

52. An Amazing Story -- Aug.19, 1999
Bruner says he saw the hand "sort of pop up in the incision" on the womb, and he "reached over and picked it up."
Samuel, now nearly 5 months old [may 2, 2000], & is “developing normally and hitting his monthly milestones. He smiles often and is nearly sitting up on his own.”
It will take years to know how much difference the surgery made, but Alex Armas [father] says he's happy the photo has been seen by millions.

53. Samuel Armas 21 weeks

54. Human Gestation 3rd Trimester Rapid growth of fetus
To about 53 cm
3-3.5 kg
Fetal activity decreases
Less room to move
Fully mature
Ready for birth

55. Parturition

56. Parturition

57. Parturition

58. Parturition

59. Parturition

60. Parturition

61. Parturition

62. Parturition

63. Parturition

64. Parturition

65. Parturition

66. Parturition

67. Parturition

68. Parturition

69. Parturition

70. Parturition

71. Parturition

72. Reproductive Technologies

73. Birth Control Sterilization Most effective
In males vas deferens is cut off and sealed
Only effects sperm content of semen so minimal side effects
In females tubal ligation or cutting of the oviducts
Disadvantages of sterilization - hard to reverse

74. Birth Control “The pill"
A combination of estrogen and progesterone given for 21 days of the 28 day cycle
Effectively shuts down FSH and LH production so follicles do not develop.
Many of the early problems have been sorted out but side effects possible

75. Birth Control Barrier Methods
Diaphragms, Cervical Caps, Vaginal Sponges, Condoms
Condom
fits over the penis and prevents semen from entering the female;
Diaphragm
which fits over the cervix and prevents semen from entering the uterus
both of these methods are more reliable when used in conjunction with a spermicidal foam or jelly

76. Birth Control IUD Inter-Utarian Device
placed in the uterus by a physician,
prevent implantation of the blastocyst in the endometrium.
Best for women who have had one pregnancy, middle to older and are at low risk for STI’s

77. Birth Control "Natural family planning"
Requires knowledge of the day of ovulation
If known, can avoid the 4 days either side of ovulation to account for unusually long -lived sperm or eggs.
Women need exceptionally regular cycles to be effective
"Basal" body temperature measurements (T rises at ovulation), vaginal pH measurements (more alkaline), mucus thickness can help determine time ovulation.

78. Birth Control "Morning after pill“
Most are essentially a controlled overdose of normal birth control pills
RU-486 now distributed by Planned Parenthood.
Blocks progesterone receptors causing uterine lining to slough off taking embryo with it.
Many people have ethical problems with these pills since they remove fertilized eggs.
i.e. after "conception" has occurred.
“abortion pill”

79. Reproductive Technologies
Ultrasound
the use of high-frequency sound waves to visualize the fetus
Amniocentesis
a long needle is used to remove a sample of amniotic fluid from the amniotic sac surrounding the fetus,
fetal cells in the fluid are cultured for 2 to 4 weeks and then analyzed for chromosomal defects and other genetic disorders

80. Amniocentesis

81. Reproductive Technologies
Chorionic Villi Sampling (CVS)
a small sample of tissue is removed from the chorion,
the fetal part of the placenta.
Can be performed earlier in the pregnancy than amniocentesis
results can be obtained within a few days
greater risk of spontaneous abortion from CVS than from amniocentesis
ethical considerations: essentially all detectable fetal disorders remain untreatable in the uterus, and many cannot be corrected even after birth

82. Reproductive Technologies
In Vitro Fertilization
ova can be surgically removed from a woman whose oviducts are blocked
These are fertilized in a petri dish in a laboratory
The resulting embryos can than be inserted into the woman's uterus (or into a surrogate mother's uterus)
Ethical considerations: post-menopausal woman can now have children; in surrogacy, who is the legal mother???

83. STIs
You need to know which STIs are bacterial (and therefore curable through antibiotics) and viral (uncurable)

84. Virus
Bacteria
HPV (human papilloma virus) – Can cause genital warts, some strains can lead to genital cancers
Chlamydia
Herpes
Gonorrhea
HIV (Human immunodefficiency virus) – Can develop into AIDS
Syphilis
This website has more information on STIs and sexual health