1. Fertilization and Development
Human Anatomy and Physiology

2. Fertilization Fusion of sperm and an ovum
Occurs in the fallopian tubes of the female
An oocyte is viable for 24 hours; sperm are viable for 72 hours.
Takes sperm 1-2 hours to complete journey up the female duct system. Must swim against the cilia current.

4. Fertilization and Implantation
Section 39-4
Uterine wall
Blastocyst
Morula
4 cells
2 cells
Zygote
Ovary
Fallopian tube
Day 3
Day 2
Day 1
Day 4
Fertilization
Day 0
Day 7
Implantation of blastocyst
Egg released by ovary

5. Cleavage A rapid series of mitotic divisions
Begins with zygote and ends with a blastocyst

6. Implantation
Blastocyst implanted into endometrium of uterus

7. The blastocyst implants
LE 46-15a
Cleavage starts
Cleavage continues
Ovary
Fertilization occurs
The blastocyst implants
Uterus
Ovulation
Endometrium
From ovulation to implantation

8. Pregnancy
Placenta
Formed when the outer layer of the blastocyst mingles with the endometrium
Connects to fetus by the umbilical cord
Serves as respiratory, nutritive, and excretory needs of the embryo
Produces hormones of pregnancy including estrogen and progesterone
Functioning by 3rd week
The tissue of the fetus releases human chorionic gonadotropin (HCG), which helps maintain the uterine lining.

9. LE 46-16
Maternal
arteries
Maternal
veins
Placenta
Maternal portion
of placenta
Umbilical cord
Chorionic villus
containing fetal
capillaries
Fetal portion of
placenta (chorion)
Maternal blood
pools
Placental circulation. From the fourth week of development until birth, the placenta, a combination of maternal and embryonic tissues, transports nutrients, respiratory gases, and wastes between embryo or fetus and the mother. Maternal blood enters the placenta in arteries, flows through blood pools in the endometrium, and leaves via veins. Embryonic or fetal blood which remain in vessels enters the placenta through arteries and passes through capillaries in chorionic villi, where oxygen and nutrients are acquired. Fetal blood leaves the placenta through veins leading back to the fetus.
Uterus
Umbilical arteries
Fetal arteriole
Fetal venule
Umbilical vein
Umbilical cord
Placental circulation. From the fourth week of development until birth, the placenta, a combination of maternal and embryonic tissues, transports nutrients, respiratory gases, and wastes between embryo or fetus and the mother. Maternal blood enters the placenta in arteries, flows through blood pools in the endometrium, and leaves via veins. Embryonic or fetal blood which remain in vessels enters the placenta through arteries and passes through capillaries in chorionic villi, where oxygen and nutrients are acquired. Fetal blood leaves the placenta through veins leading back to the fetus.

10. 20 weeks.
14 weeks.
5 weeks.

11. Pregnancy: First Trimester
Radical change for the mother and the embryo
During its first 2 to 4 weeks, the embryo obtains nutrients directly from the endometrium until placenta forms
Blood from the embryo travels to the placenta through arteries of the umbilical cord and returns via the umbilical vein
Main period of organogenesis
development of the body organs
Heart develops first
Neural tube develops
All body systems appear by Week 8 – Now a Fetus

12. Pregnancy: 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

13. Pregnancy: 3rd Trimester
More growth
Kicking, rolling, stretching
Eyes open – Week 32
Lungs mature
Rotates to head-down
position

14. Childbirth
Due Date is 280 days from the start of the last menstrual period

15. Initiation of Labor
Estrogen reaches highest level of pregnancy causing progesterone to stop quieting the uterine muscles
Leads to irregular contractions called Braxton’s Hicks (false labor)
Two more chemical signals convert false labor into real labor pains
Oxytocin
Prostaglandins

16. So….
Oxytocin and prostaglandins initiate the rhythmic, expulsive contractions of true labor
Positive feedback mechanism
stronger contractions lead to release of more oxytocin leading to even stronger contractions

17. Estrogen Oxytocin from ovaries from fetus and mother’s
LE 46-18
Estrogen
Oxytocin
from
ovaries
from fetus
and mother’s
posterior pituitary
Induces oxytocin
receptors on uterus
Positive feedback
Stimulates uterus
to contract
Stimulates
placenta to make
Prostaglandins
Stimulate more
contractions
of uterus

18. Stages of Labor Dilation Stage Expulsion Stage Placental Stage
Cervix fully dilated by baby’s head to 10 cm.
Cervix softens
Water breaks (amniotic fluid released)
Lasts 6-12 hours
Expulsion Stage
Time from full dilation to delivery of baby
Can take as long as 2 hours, typically 50 minutes (20 minutes if not first child)
Placental Stage
Delivery of placenta
Takes 15 minutes

19. Dilation of the cervix
Expulsion: delivery of the infant
Placenta
Cervix
Uterus
Umbilical
cord
Delivery of the placenta
(detaching)

20. Contraception and Abortion
Contraception, the deliberate prevention of pregnancy, can be achieved in a number of ways
Some general contraceptive methods:
Preventing release of eggs and sperm
Keeping sperm and egg apart
Preventing implantation of an embryo
Abortion is the termination of a pregnancy

21. Meeting of sperm and oocyte Implantation of blastocyst
LE 46-20
Male
Female
Method
Event
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
Abstinence
Condom
Coitus interruptus
(very high failure
rate)
Sperm
deposited
in vagina
Capture of the
oocyte by the
oviduct
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
Progestin alone
Implantation of blastocyst
in properly prepared
endometrium
Birth