09 Prenatal Stage of Development The prenatal stage of development can be taken down in three stages The germinal or zygotic stage which is the first 2 weeks The embryonic stage which continues from the 2nd week through the 8th week Fetal stage which begins the 9th week and lasts until birth The Germinal Stage During the germinal stage there is rapid cell division and by 5 days the zygote has become a 100 cell organism called a blastocyst The Embryonic Stage During the Embryonic Stage the cells begin to specialize and major organ and systems are developed It s during this time the most miscarriages occur and genetic defects surface The Fetal Stage During the fetal stage growth continues and by the end of the 6th month 24 weeks the fetus reaches viability meaning the organs are developed enough that it has a possibility of surviving outside the womb with intensive neonatal care During the last 3 months the fetus is responsive to sound light and touch in womb Prenatal Environment There are sensitive periods when organs and systems are more vulnerable to the effects of teratogens which can be anything in the environment with a potential for harm Certain organs and systems are more vulnerable to teratogens during particular stages of prenatal development The most severe effects are most likely to occur during the embryonic stage A good example is Fetal Alcohol Syndrome FAS which can be result of drinking alcohol
View Full Document
Unlocking...