By the time a woman found out that she’s pregnant, implantation have occurred.
**Week 1 of pregnancy **- starts on the last day of the previous menstrual cycle. There is no actual baby at this week. No ovum was released.
**Week 2 of pregnancy **- Ovum is usually released on the last day of week 2, or the first day of week 3 (plus or minus).
-Lifespan of an ovum is only about 24 hours, so conception usually happens less then a day after ovulation.
-Scientist and doctors have confirmed that life begin at conception, no matter what public opinions is. Without life, cell cannot divide and grow. And they agreed that zygote (single cell), blastocyst (70-100 cells) consist of human life.
-Zygote fulfills the four criteria of biological life. the criteria is
- metabolism,
- growth,
- reaction to stimuli, and
- reproduction.
-The debate here now is whether zygote is a human being, or has a human right.
First day of conception - Zygote. Contain complete human DNA that will determine it’s characteristic (gender, race, eye color, hair color, height, etc) in the future. The DNA cannot be changed or edited. Cell starts to divide immediately after conception.
Zygote develops from 1 celled stage to 2-celled stage, and slowly divide to 4-celled staged, 8-celled stage and go on. they subdivide every 12-20 hours. Identical twins usually occurs at this stage (between 2 celled stage to 16 celled stage time)
3-5 days after conception, zygote has now become morula. Morula consist of at least 32 cells. It continues to develop to blastocyst.
Blastocyst consist of outer cells which forms a hollow ball (like a hollow egg shell) which will become placenta and other supporting tissues, and other and a centered cells group which will become fetus (a human being)
by the last day of week 2 pregnancy or the frist day of week 3 pregnancy, implantation occurred. This is when the medical pregnancy begins.
**Week 3 pregnancy **- after implantation, women had no idea that they are pregnant at this stage yet. Even the very sensitive pregnancy test kit cannot detect pregnancy at this stage.
around 2 or 3 days of week 3 pregnancy, primitive placental blood circulation has begun. The embryo now its very own distinctive blood type from the mother.
The embryo’s form at this stage looks like a DVD disc.
Brain starts to develop during this week.
**Week 4 pregnancy **- usually pregnancy can be detected by pregnancy test kit at the first day of week 4. However, false negative are also common and some women take longer days for their pregnancy to be detected.
the embryo now has 3 layers.
inner layer consists of cells that will develop into lungs, liver, and digestive system.
middle layer consists of cells that will develop into bones, muscles, kidneys, sex organs and heart.
outer layers consist of cells that will develop into skin, hair, eyes, and nervous system.
Week 5 pregnancy - 3 weeks after fertilization. baby looks like this.
http://www.deathroe.com/baby_development/images/week1_3.jpg
It has heart beat (since the first day of this week) and is pumping a different blood type from the mother, has a primitive intestine, and a neural tube, and a brain. it has arms and leg, and individual fingers, and even fingerprints.
Week 6 pregnancy - it has eyes.
I think I better stop here. it’s going to be a looooooooooong post.
As to whether zygote or embryo is human being, humans are funny creatures.
When they are expecting babies, the mother and father will call the zygote or embryo " the baby", “my baby”, etc even knowingly it’s only few cells. When they do not want the baby, or encouraging “right to choose abortion” they start to list down a long list as to why a zygote or embryo or even fetus cannot be a human being. By this logic, one can say “My baby wasn’t a human being”.
Pro-choice, you decide. P/S: sorry for my poor English command.
