Fetal Development Lab

1. Oocyte is Fertilized: When the egg is fertilized by the males sperm is considered the first day of post-ovulation or the Carnegie stage I in the first trimester.

This is the first major event for in a babies development. Before this there is just an egg and some sperm and after fertilization there is the makings of a new person. Figure 1.1

2. The Fetus attaches to the uterus: this is Carnegie Stage 4 in the first trimester about 5-6 days after fertilization.

In this stage the egg attaches itself to the uterus and creates the connection with the mothers uterus. From this connection new blood capillaries will develop and circulation of critical nutrients, oxygen, and hormones (progesterone) will be exchanged allowing the pregnancy to continue. Figure 1.2

3. The Three cell layers develop: This is Carnegie Stage 6 in the 1st trimester and happens about 13 days into development.

This stage is very important the three major cell layers start to develop. These are the ectoderm, medoderm, and endoderm. From these three layers all organs, bones, tissues, and body systems will develop.

4. The creature takes shape: This stage is still in the first trimester and is 23-25 days into development.

At this point the fetus starts to take on a shape as internal organs start to form. The heart is beating but circulation is not yet complete, however the central nervous systems is the most developed system. Figure 1.3

5. Spontaneous movement begins: this stage is between 51-52 days into development and is Carnegie Stage 20.

This stage is where the mother can actually start feeling the baby move with spontaneous kicks. This would be important because for the baby to be moving it means it is developing well with all major organs and systems well into development, and the brain is sending nerve signals to the body. Figure 1.4

6. Brain Structure complete: In this stage the baby is well into development, 10 weeks or so and is now in the 2nd trimester.

In this stage the Brain structure is complete and will start to increase in size very rapidly. Intestines and digestive tract are contracting and producing enzymes. The baby starts to develop reflexes and becomes very sensitive to movement.

7. The babes Sex: During the 2nd trimester about 14 weeks into development the babies sex organs are developing and visible.

At this stage it is easy to tell if the baby is a boy or a girl as the sex organs are clearly visible in ultrasound scans. All other organs and systems are getting larger and the baby is increasing in size rapidly. Figure 1.5

8. Bone marrow: This stage occurs about 20 weeks into development and is still in the 2nd trimester.

This is the stage were the fetus bones start to develop its own blood cells, this will become very important because blood cells are responsible for carrying oxygen. The brain is also experiencing rapid growth and development and the babies limbs are developing and growing larger.

Figure 1.6

9. Immune System: At this point the fetus is at 32 weeks of development and in the 3rd trimester.

During this stage of development the immune system starts to develop. This is extremely important for the baby, with out a well developed immune system the baby will have a hard time fighting of infections and disease. At this point the babies eyes are open when it is awake and close when it sleeps.

10. Fully developed Fetus: It has been between 38 and 40 weeks since the egg was fertilized and the final stages of the third trimester.

Now the baby is quit large with hair and fully developed organs. Most organs are developed and working and red blood cells are being produced by the liver. The baby is basically ready to be born and begin breathing and developing out side of the mothers uterus. Figure 1.7