Prenatal development refers to the various stages through which a human embryo undergoes during pregnancy. Prenatal development stages usually start immediately after fertilization of the ova and ends at birth.During the zygotic or germinal stage, the zygote moves toward the uterus. This takes approximately one week. This stage is also characterized by extensive cell divisions in which the zygote divides itself into paired cells (Sigelman & Rider, 2010). Upon reaching the eighth cell, cell division temporarily stops and the cells become differentiated. Consequently, each cell acquires specific characteristics that will later on determine its type. The cells then multiply further and separate into two distinctive masses. At this stage, the outer cells become the placenta while the inner cells form the embryo. Cell division continues until the cells form a blastocyst. The blastocyst is made up of three major components, the ectoderm which develops into skin and nervous system, the endoderm which develops into digestive and respiratory system and the mesoderm which becomes the muscle and skeletal system.
Embryonic Stage. After the zygotic stage, the masses of cells form embryo. The embryo is usually formed at the beginning of the third week (Hamilton, 2011). At this stage, the mass of cells develops into a distinct human being. The embryo further divides into three layers which form the body systems. Between the 22nd to 25th days of inception, the neural tubes begin to form. The neural tube later develops into the central nervous system that forms the spinal cord and the brain. In the fourth week, the head develops, followed by the eyes, nose, ears and mouth. The cardiovascular system also begins to appear and the heart is formed. On the fifth week, the arms and legs develop. According to Sigelman and Rider (2010), basic body organs and parts usually develops by the eight week, except the sex organs.
Resilience in Infants. Infants usually become resilient after developing red bloods cells in the womb. However, the resilience increases rapidly after birth and it is facilitated by adequate breastfeeding. The colostrums are often cited as the best provider of resilience and protection to infections in children after birth.