Correct Answer - Option 4 : All the above
Prenatal development is the process in which an embryo or fetus, gestates during pregnancy, from fertilization until birth.
- Most physiologists and members of the medical profession believed that most development takes place before birth.
- It is the first but shortest period for the newborn baby or infancy, which starts from conception and ends at the birth time of the baby. This period is approximately 270 to 280 days or nine months of a calendar
- During the prenatal period, proportionally greater growth and development take place than any other time throughout the entire life of a human.
- The prenatal period is ten lunar months of twenty-eight days each in length or nine calendar months. However, the period can and does vary greatly in length, ranging from 180-334 days.
The prenatal period is divided into three stages.
Germinal stage (fertilization to the end of the second week)
- Two halves of genetic material from father and mother come together to form a unique combination of genetic potentialities when the sperm fertilizes the egg.
- Less than two days after the sperm unites with the egg, the zygote divides into two cells. Then these two cells each divide again, and the process of division goes on, forming in nine months a new human being.
Period of Embryo (end of the second week to end of the second lunar month)
- The embryo develops into a miniature human being. This stage begins on the 15th day after conception and continues until about the 8th week, or until the embryo is 1.2 inches in length.
- During this period the cells of the embryo are not only multiplying, but they are taking on specific functions. This process is called tissue differentiation.
- At the 8th week (1 inch, 1/15 ounce) embryo now resembles a human being. The facial features continue to develop and the external ear appears. Also, we see the beginnings of external genitalia.
Period of Fetus (end of the second lunar month to birth)
- At this point, the embryo is developed enough to call a fetus. All organs and structures found in a full-term newborn are present. The head comprises nearly half of the fetus’ size and the face is well-formed at weeks 9 to 12
- At 38 weeks (19 to 21 inches 7 or 8 pounds) the fetus is considered full term. It fills the entire uterus, and its head is the same size around as its shoulders.
Hence, the prenatal period has been divided into three parts germinal, embryo and fetus.
