Embryo
After the first week and up to the eighth week of the product of your conception is called an imagine that your own little embryo has a which looks like a large bulge at the chest front? I’, rudimen- tary brain and spinal cord are also present. Shallow pits onthe sides of the head show where eyes and ears will later grow. In size, picture anywhere from one-quarter inch to one and one-tenth inches long. At this point, you haven’t even missed your period yet. In fact, that rich, spongy lining in your uterus, which served the implantation adventure quite well, is what would have been shed during regular monthly menstruation. Because you have an embryo growing, changing, and manufacturing profound changes in your womb. you miss this monthly event, experiencing one of the first clear signs of pregnancy. The embryo is secreting a hormone, known as human chorionic gonadotropin (HCG), into your blood system, which interferes with menstruation. This is the hormone that will appear in your urine on a pregnancy test and alert you to the news of a new life beginning.
By the end of the first real lunar month (four weeks) of growth, some of the rapidly dividing cells inside this little “blister” form the placenta, growing more inroads into your uterine cavity and paving the way for its expanding job of nourishing the unborn baby. Inside, the embryo is lengthening and becoming encapsulated in what appears to be a water-tight balloon sac, called the amnion. Fluids from your own body fill the sac and cushion your baby from all the bumps, lumps, and movement in your busy life. Known as the amniotic fluid, this watery substance keeps a consistent temperature and provides a weightless environment that allows the developing baby to exercise and move around. Next to the embryo another little sac appears. Called the yolk sac, this teeny cluster of cells always floats nearby, consists of tiny blood vessels, and provides the blood for the embryo, which is still too immature to do so for itself.