Embryonic Stage

Reviewed by Ashley Wong, MS, Clinical EmbryologistCheckmark | Last updated: April 16, 2020

What Does Embryonic Stage Mean?

The embryonic stage of human fetal development refers to weeks 2 to week 8 of development after an egg is fertilized.

The embryonic stage is when most of the organs and body structures begin to develop. As a result, this is a very fragile stage of development and there is potential for malformation leading to miscarriage.

FertilitySmarts Explains Embryonic Stage

There are three major stages of gestation:

  1. Pre-embryonic stage - From fertilization to week two of development when a fertilized egg develops into a blastocyst that implants into the uterine lining.
  2. Embryonic stage - From the 2nd-week post-fertilization to the 8th week of development.
  3. Fetal stage - From around 9 weeks after fertilization and ends with birth.

The embryonic stage is a period of rapid cellular development. During this time, precursors to almost all of the body organs and structures are formed. This is accomplished by rapid cell division, movement, and differentiation.

As a result, this is a very fragile stage of development and there is potential for malformation. During this stage, the embryo is also sensitive to environmental agents such as viruses and other teratogens (agents that can cause birth anomalies).


Embryonic Period

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