1. Pregnancy

2. Fertilization
During intercourse, millions of sperm are released from the male and into the female.
Only about 100 sperm will make its way to the fallopian tubes.
Those 100 sperm try to penetrate the outer egg with only one sperm being successful.
Once the head of the sperm breaks through the egg, the egg releases a protein that prevents other sperm from entering the egg. (WOW the human body is so amazing.)
High level of progesterone is released and this stops the menstruation cycle.

3. Fertilization
The cell membrane of the sperm will then fuse with the egg to produce the zygote. The zygote now has the DNA it needs to create the offspring – one set of 23 chromosomes from mom and the other set of 23 chromosomes from dad.
Upon a successful fertilization, the zygote grows for nine months (38 weeks) inside the mother to be and ends with the birth of an offspring.
The nine months are divided into three trimesters (three months per trimester).
Video on fertilization

4. First Trimester
The first trimester starts from fertilization and ends after three months.
The zygote – now an embryo – begins cell division in the fallopian tube and within one week will make its way to the uterus.
Once it gets to the uterus it will attach to the wall of the uterus - endometrium.

5. First Trimester
Here the embryo creates a sac that is filled with amniotic fluid and the umbilical cord is created to combine the mother to the embryo.
Amniotic fluid supports, protects, and maintains a warm environment for the embryo until birth.
Once the uterus realizes it has a zygote, and not an un-fertilized egg, the body releases hormones to prevent the menstruation cycle.

6. Frist Trimester
The following is the path of a fertilized egg.

7. First Trimester
Here is a labelled diagram of the fetus after it attaches itself to the uterus wall.
This is called the placenta, it provides oxygen and nutrients to the growing baby and removes the baby’s waste products.
The umbilical cord connects the baby to the placenta and helps facilitate the oxygen and nutrients between the placenta and baby.

8. First Trimester
All the cells are reading the DNA and starting to create the offspring.
By the fourth week the brain and a nervous system have been developed and the heart is beating.
By the end of week five the eyes, ears and nose are noticeable; as are the limb buds (small little hands and feet) and the tail (which becomes the tailbone) are visible.

9. First Trimester
By the end of the eighth week the embryo has started to develop the beginning of all the organs and is now called a fetus.
The fetus looks like a human being, however it is only the size of a lima bean.
Through the umbilical cord the fetus and mother are able to share nutrients, oxygen, and the the fetus’ waste.
By the end of the third month, muscles and bones are starting to form. The heart is beating, blood is circulating through the fetus and sex organs are forming. It is at this point you can determine the sex of the baby.
The fetus is about 12 cm long and weighs approx. 50 grams

10. Second Trimester
Through months four – six the fetus starts to really take shape.
It grows from 8 cm to 30 cm long.
The heartbeat can be heard by a stethoscope.
Movements can be felt by the mother – especially now that he abdomen is starting to swell as the fetus gets bigger.
By 24 weeks (or approx. 6 months) the fetus resembles a tiny infant. Fingers and toes have elongated. Facial features start to develop.
Oxygen is still being pumped through the umbilical cord.

11. Second Trimester Image of a fetus in the second trimester
Notice the hands, face, nose, ears, eyes and etc… as they are starting to become more developed.

12. Third Trimester
During months seven - nine the fetus puts on more mass.
It starts to have sleeping and waking patterns, and it reacts to stimuli from the outside world (i.e. music, sound, movement and etc…)
The lungs continue to mature, and the final development of the body comes to an end just before delivery.
The fetus fills the capacity of the uterus, its body turns around with its head pointing towards the cervix and the birth canal in preparation for delivery.
At 37 weeks, the fetus is considered to be full term and ranges from 45 – 55 cm and can weigh up to 4.5 kg (10 lbs)

13. Third Trimester
In the thrid trimester, the fetus has fully formed, there is no room left for it to grow in the uterus and is ready for delivery.

14. Twins Fraternal twins Identical twins
When two eggs, one in each fallopian tube, are released and both are fertilized at the same time.
Each embryo develops its own placenta.
While they are twins, their genetic material is different and they are not identical.
Identical twins
One egg is fertilized, but during mitosis the egg splits into two creating two embryo’s.
Both embryo’s share one placenta.
Since they are created from one sperm and one egg, these twins share the exact same genetic material and thus look identical.

15. Growth Progression

16. Birth
The first sign that identifies that the baby is ready to be born is when the muscles of the mothers uterus start to contract regularly (like every 15 – 20 minutes and lasting for as long as 40 seconds). This is the body’s natural way to start delivery, it is at this point labour has begun.
The second sign is the breaking of the water.
During labour, hormones start to control the process of delivery, and while the mother is able to use her abdominal muscled to help with delivery, it is her body and the hormones that start and play an vital role in the delivery process.

17. Birth
First – the cervix begins to dilate (open up). It has to fully dilate to 10cm.
The membrane surrounding baby is then forced into the birth canal (the Vagina).

18. Birth
Second – the amniotic membrane breaks, and amniotic fluid lubricates the birth canal. This is called the breaking of the water.

19. Birth
Third – Once the cervix has widened to 10 cm, uterine contractions (this is done via the hormones being released during labour) push the baby’s head into the birth canal.

20. Birth
Fourth – When the head and shoulders are free of the birth canal, the rest of the baby slips out easily – usually with the help of a nurse or doctor.
After the baby is born, the placenta is pushed out of the uterus. Once the baby is able to breath on its own, the umbilical cord is cut and tied to prevent bleeding.
The “belly – button” is the scar from the umbilical cord.

21. Assignment
Pg 121 – 2, 3, 4, 5, 7, 8, 11, 12, 13, 16, 17, 18, 19

22. Stem Cells
Stem Cells – are unspecialized cells that have the ability to reproduce themselves. They have not yet reached the point where they divide into specialized cells (like our hair, ears, and etc…).
We can use these cells to help rebuild organs and other parts of the bodies that have been damaged. For example, they can be placed near the heart muscled of someone who had a heart attack. The stem cells are then able to read the person’s DNA, and at the same time rebuild a new heart muscle.

23. Stem Cells
Problem, stem cells only survive in bone marrow, the umbilical cord and in an embryo.
Getting cells from bone marrow is EXTREMELY PAINFUL.
Keeping the umbilical cord frozen so it does not deteriorate is VERY EXPENSIVE.
But through in vitro fertilization, we can fertilize many eggs, and since only one of them is going to be used, what do you do with the other fertilized eggs? You could grow them to an embryo and then extract the stem cells from it, then destroy the embryo.
The last option is less expensive than freezing the umbilical cord, and is not as painful as getting bone marrow – but theoretically you are going to be killing a fertilized egg that could become an offspring…