sikiönkehitys

Sikiönkehitys, also known as fetal development, refers to the process of growth and differentiation that occurs from the time of conception until birth. This complex journey begins with a single fertilized egg, the zygote, which undergoes rapid cell division and specialization.

The earliest stages involve the formation of the blastocyst, a hollow ball of cells that implants in the uterine wall. Following implantation, the embryonic period begins, during which major organs and body systems start to form. This period is critical, as the developing embryo is particularly vulnerable to external factors. Key structures like the neural tube, heart, and limb buds emerge during these initial weeks.

After approximately eight weeks of gestation, the developing organism is called a fetus. The fetal period is characterized by rapid growth, maturation of existing organs, and the development of distinct physical features. By the end of the second trimester, most major organ systems are functional to some degree. The third trimester focuses on further growth, weight gain, and the refinement of bodily functions in preparation for life outside the womb. Throughout sikiönkehitys, a delicate balance of genetic programming and environmental influences guides the formation of a new individual.