Unit 1 Section 2: Genetics

Early Fetal Devolopment

The creation of life is truly a miracle. It's amazing to learn all the steps that our bodies go through to create this little tiny human being. And that fact that our bodies do it all on their own. From the moment of conception the body start rapidly making these changes. Immediately after fertilization, the zygote divides repeatedly and passes down the oviduct to the uterus. The actual embryonic development starts the second week and last until the end of the second month.
Week 3: Nervous system and heart develope.
Weeks 4 & 5: Umbilical cord starts to form. Buds that will eventually be arms and legs develop, head enlarges and organs become more prominent.
Weeks 6 - 8: Heart develops and usually starts beating around 24 days after conception. Embryo changes to a form easily recognized by humans. Nervous system is developed well enough to have reflex actions.
3 - 4 months: Chance of miscarriage significantly declines. Cartilage begins to turn into bone. Tooth buds are starting to form.
5 - 6 months: Hair beginning to grow on babies head. Eyelashes, eyebrows, and eyelids appear. Around the 6th month the eyelids will start to part and the baby can open it's eyes for short periods of time.
7 - 8 months: Taste buds have developed. Fat layers are forming and organs have are maturing. By the 8th month most organs are developed with the exception of the lungs. Tremendous brain growth is happening at this time.
9 months: Baby is now fully developed and ready to survive outside it's mother.