Prenatal Development-The Miracle of Life
Have you ever thought about what an absolute miracle your life is? Imagine how you came to be. Out of thousands of eggs and millions of sperm, one egg and one sperm united to produce you. Had the union of sperm and egg come a day or even a month earlier or later, you might have been every different, maybe the opposite sex or with blonde hair of longer legs. Conception occurs when a single sperm cell from the male unites with an ovum (egg) in the females’ fallopian tube in process call fertilization. The fertilized egg is called a zygote. By the time the zygote ends its three to four day journey through the fallopian tube and reaches that uterus, it has divided into approximately 64 to 128 cells…show more content… Like the placenta and umbilical cord, the amnion develops from the fertilized egg, not from the mother’s own body. Amniotic fluid helps to cushion and protect the fetus against physical shocks and trauma and provides an environment that is temperature, humidity, and pressure controlled. At approximately 16 weeks, the kidneys of the fetus begin to produce urine. This fetal urine remains the main source of the amniotic fluid until the third trimester, when some of the fluid is excreted from the lungs of the growing fetus. Although the amniotic fluid increases in volume tenfold from the 12th to the 40th week of pregnancy, it is also removed in various ways (Challis & others, 2001). Some is swallowed by the fetus, and some is absorbed through the umbilical cord and the membranes covering the placenta.
The placenta consists of a disk-shaped group of tissues in which small blood vessels from the mother that the offspring intertwine but do not join. The umbilical cord contains two umbilical arteries and one umbilical vein and connects the baby to the placenta. Very small molecules, oxygen, water, salt, food from the mother’s blood, as well as carbon dioxide and digestive wastes from the embryo’s blood, pass back and fourth between the mother and embryo (Bush & others, 2001). Large molecules cannot pass through the placental wall; these include red blood cells and harmful