What Are the Stages of Embryonic Development?


Quick Answer

Stages of embryonic development include implantation, differentiation and gastrulation. The process of embryonic development is medically referred to as embryogenesis, according to Study.com. This stage lasts until the 10th week of pregnancy.

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Full Answer

Implantation happens when the blastocyst is implanted completely into the uterine tissue, which also marks the end of the germinal period. A blastocyst is what forms when the zygote, the single cell formed from an egg and sperm, begins to implant itself into the uterus, explains Study.com. After full implantation, the blastocyst divides rapidly. This is when the process of differentiation begins.

During differentiation, cells assume different functions. The first part of this process is a cell division that creates the placenta and the cells that comprise the baby, says Study.com. After differentiation, the gastrulation process begins. This is the process that forms the three layers of the embryo. The outer layer is referred to as the ectoderm, the middle layer is the mesoderm and the innermost layer is dubbed the endoderm.

Each layer of the embryo creates different bodily structures. The ectoderm is responsible for forming the skin, hair and nervous system. The mesoderm is where the lungs, bones and muscles form, and the endoderm forms internal organs such as the bladder and digestive tract, states Study.com. Once the essential body parts are formed, the embryonic period ends and the fetal stage begins.

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