An embryo (/ ˈɛmbrioʊ / EM-bree-oh) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins …

Dec 28, 2025 · In humans the term is applied to the unborn child until the end of the seventh week following conception; from the eighth week the unborn child is called a fetus. A brief treatment of …

: an animal in the early stages of development that are marked by cleavage, the laying down of the basic tissues, and the formation of primitive organs and organ systems compare fetus. : a tiny young plant …

Oct 14, 2025 · Timing is what sets apart an embryo from a fetus. Learn more about the stages of your baby’s development here.

Use the stage number links to images and information about each specific stage of human development over the first 8 weeks. The links below give a broad overview of developmental events during each …

Not only do embryos get bigger during that time, but they also go from being just a simple, single, cell to being the many cells that make up a human. All of a human’s features, organs, and body systems …

Aug 13, 2023 · In Biology, an embryo is designated as the initial phase of development for a multicellular organism arising after the fusion of a sperm cell (male sex gamete) and an egg cell (female sex …

The external genitalia are apparent, but at this point, male and female embryos are indistinguishable. Bone begins to replace cartilage in the embryonic skeleton through the process of ossification.

Jul 22, 2025 · Human embryo development begins with fertilization, the union of a sperm and an egg, typically in the fallopian tube. This fusion forms a single-celled zygote, containing a complete set of …

Dec 23, 2025 · Scientists have developed an experimental way to study how human embryos implant in a uterus, which may provide new insights into why miscarriages occur and how they can be prevented.