embrionului

Embrionul is the term used to describe the early stage of development of a multicellular organism. In humans and other mammals, it begins after fertilization, when the sperm fuses with the egg to form a zygote. This single cell then undergoes rapid cell division and differentiation, gradually forming the various tissues and organs of the developing organism. The embryonic period is characterized by significant growth and structural changes.

The development of an embryo is a complex and highly regulated process. Following fertilization, the zygote travels down the fallopian tube towards the uterus. Once in the uterus, it implants into the uterine wall, establishing a connection that will provide nourishment and oxygen. During this early phase, the embryo develops distinct layers that will give rise to specific organ systems. For example, the ectoderm will form the skin and nervous system, the mesoderm will develop into muscles, bones, and the circulatory system, and the endoderm will give rise to the digestive and respiratory systems.

The embryonic stage is critical for the establishment of the basic body plan. By the end of the embryonic period, which in humans is typically around the eighth week of gestation, most major organs and body structures are formed, though they are still immature and continue to develop. Following this stage, the developing organism is referred to as a fetus, and the focus shifts to growth and maturation of the already formed structures until birth. The study of embryonic development is known as embryology.