Here is a brief description of external embryonic development between week 3 to 8.

In Week 3 the embryonic disc forms

Amniotic sac removal shows the epiblast layer

Gastrulation occurs at the primitive node and streak

Axial process and axes are established

The disc folds ventrally

The embryo is now 2 mm long

Watch embryo growth from week 4 onward

In week 4, somites, neural plate folding and formation of the heart

In week 5, sensory placodes, pharyngeal arches and limb buds develop

In week 6, external ear primordia and the limb plates appear

In week 7, upper lip and maxilla fuse and limb digital rays appear

In week 8, limbs grow and have mature form

The external ear fuses and eyelids can be seen

There is also overall growth in size

That has been a quick external view of human embryonic development.

Author:	Kerrie Arnhold (via theBox)
Created:	15/05/2016
Updated:	22/09/2025
Theme:	Default
Tags:	embryology 1 minute embryology BGDA medicine
Copyright:	All Rights Reserved

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