A newly developing human is typically referred to as an embryo until the ninth week after conception, when it is then referred to as a fetus. In other multicellular organisms, the word embryo can be used …

Dec 28, 2025 · An embryo is the early developmental stage of an animal while it is in the egg or within the uterus of the mother. In humans the term is applied to the unborn child until the end of the …

: 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 …

embryo An organism in its earliest stages of development, especially before it has reached a stage at which it can be distinguished from other species. The human embryo is so called up to the eighth …

Jul 21, 2025 · An embryo represents the initial stage of development in a multicellular organism. This period is characterized by rapid cell division and the establishment of the basic body plan.

Aug 13, 2023 · An embryo is a newly fertilized egg (zygote) up till the eighth week of development as it transforms through the morula, blastula, gastrula, and organogenesis stages.

Oct 14, 2025 · An embryo is the early stage of development and lasts from week five to week 10 of pregnancy. A fetus is the later stage of development and lasts from the end of week 10 until birth.

2 days ago · embryo (plural embryos or embryones) Depiction of a human embryo at the ninth week. (1891) In the reproductive cycle, the stage after the fertilization of the egg that precedes the …

In humans, the embryo is defined as the organism from the time of implantation in the uterus until about the eighth week, while the fetus is the stage from this time until birth.

About 10 to 12 days after fertilization, the blastocyst is considered an embryo. When an embryo is three weeks old, a spine begins forming, as does the tissue that will become the heart. A spherical shape …