Jan 30 2008
Embryonic Development
I really enjoyed learning about fertilization in last night’s lecture. I think it is amazing how a tiny ball of cells develops into a fetus with complex body systems. Pregnancy is measured in trimesters from the day of your last menstrual period, totaling 40 weeks. The first trimester is the period that really interests me. The first trimester of pregnancy includes weeks 1-12, or about 3 months.
Actual pregnancy begins at the time when the egg is fertilized by the sperm cell. During the following week the fertilized egg grows into a microscopic ball of cells (blastocyst), which implants on the wall of the uterus. This implantation triggers many hormonal and physical changes in the body. The third-eighth weeks are called the embryonic stage, during which the embryo develops most major body organs. During this stage the embryo is highly vulnerable to damaging substances such as alcohol, radiation, and infectious disease.
Having reached a little more than 1 inch in length by the 9th week of growth, the embryo is now called a fetus. By this time, the uterus has now grown from the size of fist to about the size of a grapefruit!!
One Response to “Embryonic Development”
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Bri,
I just wanted you to know that I had made it to your blogspot and that it does now seem to be functional! And it is very artistic…as well as very well written! To date it is the single blogspot that most matches what I was hoping everyone’s blogs would do - inform and educate your readers and stretch each students understanding of lecture topics…Good for you! And you are now 20 points “richer”!
Dana