Slide 1

Human Reproduction and Development Fertilization Pregnancy Development Birth

Slide 2

Human Reproduction and Development Sperm

Slide 3

Slide 4

3 Steps of Fertilization 1.Capacitating Acidic environment of the female reproductive tract causes small pores to open in the acrosome (enzyme-loaded head) of the sperm

Slide 5

3 Steps of Fertilization

Slide 6

1.Capacitating Acidic environment of the female reproductive tract causes small pores to open in the acrosome (enzyme-loaded head) of the sperm 2.Acrosomal reaction Enzymes released from acrosome digest the outer membrane surrounding the egg cell

Slide 7

3 Steps of Fertilization 3.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

Slide 8

Fertilization Fertilization must occur within a very short window of opportunity. Egg is only fertile for 12-24 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

Slide 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

Slide 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

Slide 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

Slide 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

Slide 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

Slide 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

Slide 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.

Slide 16

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

Slide 17

Pregnancy

Slide 18

Slide 19

Childbirth Also called parturition 38 42 weeks from conception Average = 40 weeks Three stages of childbirth 1.Labour 2.Delivery 3.Afterbirth

Slide 20

Childbirth 1.Labour Involuntary Rhythmic contractions of the uterus Causes cervix to open Diameter = 10 cm 2.Delivery Involuntary uterine contractions Conscious abdominal contractions Mother forces baby out through cervix and vagina

Slide 21

Childbirth 3.Afterbirth Immediately after delivery Blood vessels in placenta contract Placenta separates from uterine wall Expelled by muscle contractions

Slide 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

Slide 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

Slide 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

Slide 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

Slide 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

Slide 27

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

Slide 28

Fetal Development Umbilical cord Connection between mother and baby Belly-button to placenta Carries babys blood to and from placenta

Slide 29

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

Slide 30

Slide 31

Embryonic Development A blastocyst undergoes gastrulation Series of cell movements and shape changes Produces an embryo with 3 cellular layers 1.Ectoderm Outer layer of cells Will become skin and nervous system 2.Mesoderm Middle layer of cells Skeleton, muscles gonads, kidneys, circulatory system 3.Endoderm Inner layer of cells Liver, pancreas, lungs, lining of digestive tract

Slide 32

Gastrulation

Slide 33

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

Slide 34

Human Gestation 1 st 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.

Slide 35

Human Gestation 1 st 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

Slide 36

Gastrulation

Slide 37

6 weeks

Slide 38

Gastrulation 7 weeks

Slide 39

Gastrulation 8 Weeks

Slide 40

8 weeks

Slide 41

10 Weeks

Slide 42

11 Weeks

Slide 43

Slide 44

14 Weeks

Slide 45

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

Slide 46

Gastrulation 18 weeks

Slide 47

47 The Hand Picture May 2, 2000 USA Today

Slide 48

48 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.

Slide 49

49 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.

Slide 50

50 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."

Slide 51

51 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.

Slide 52

Samuel Armas 21 weeks

Slide 53

Human Gestation 3 rd 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

Slide 54

Parturition

Slide 55

Slide 56

Slide 57

Slide 58

Slide 59

Slide 60

Slide 61

Slide 62

Slide 63

Slide 64

Slide 65

Slide 66

Slide 67

Slide 68

Slide 69

Slide 70

Slide 71

Reproductive Technologies

Slide 72

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

Slide 73