Ectoderm development

There are 3 basic periods in embryology:
1.Germinal period (1st 3 weeks)
2.Embryonic period (3rd week to end of 2nd month)
3.Fetal period (third month onwards)

The ectodermal differentiation described by the models occurs during the embryonic period. The head end of the ectoderm is broader than the tail end. A part of the ectoderm thickens to form the neural plate. The ectoderm is the germ layer facing the amniotic cavity. It also gives rise to a number of other structures such as the neural folds, notochord, etc. and all of these have their own separate special derivatives. The neural groove between 2 neutral folds later forms the neural tube which gives rise to highly important structures such as the brain, spinal cord, etc. The surface ectoderm forms the epidermis of all the skin in the body. When I had first seen the white coloured model, I found it really very funny because neither I nor any of my colleagues knew what it was... we weren't taught ectoderm by that time actually... we used to wonder what it was and whether it was related to embryology even! It looked like a face (with neural folds as eyes, the primitive streak as a nose and 2 lips) with a hood (cut edge of amnion) on the face....hahaha....XD.