Essay On Fetal Development

760 Words 4 Pages
Fetal Development
Fetal development is the growth and maturation of the fetus in utero (Fetal Developmet, 2009). It is divided into three periods: the zygote period, the embryonic period, and the fetal period. In the short span of two-hundred and sixty-six days a single fertilized cell develops into a human newborn infant (Figure 1). Interest has increased in the prenatal period as a staging period for well-being and disease in later life. It has enormous attention devoted to the hypothesis of fetal programming (DiPietro, 2008)
It all begins when a female’s egg and a male’s sperm come together. During a fertile male’s ejaculation a single teaspoon of his seminal fluid contains two-hundred to five-hundred million sperm. Only a few hundred complete the six or seven inch journey to the fallopian tubes where an egg arrives monthly. If the egg is present sperm simultaneously burrow their way through the eggs outside (Figure 2). Chemical changes occur that block out all other sperm when a single sperm penetrated the egg’s cellular wall. The nuclei of the egg and sperm then fuse and the independent 23 sets of chromosomes are interchanged. This is conception. A living organism is now growing inside the female. It will live off of its host by
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During this period body structures and internal organs develop. Dramatic changes occur during this stage. At week 3 the embryo is about two millimeters long and looks comparable to a salamander. At week eight the embryo is somewhat more human with nubs for arms and legs. The brain and nervous system are developing rapidly. The heart has been beating for nearly a month. All organs are in place in some kind form. The embryo’s gender was not apparent until now. Only at this point do male and female characteristics emerge (Thomas, 2013). The embryo has gone through major development. However it is still too small for the mother to sense its

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