Gastrulation

Front 1

Embryonic Disk

Back 1

Made up of the ICM, which separate into the epiblast, (epi = above), and the hypoblast, (hypo = below).\
High columnar in appearance
Cells from the epiblast form all parts of the embryo itself.

Front 2

Epiblast

Back 2

Separates into two layers to form the amniotic cavity.
Only the epiblast cells in contact with the hypoblast will form the embryo.
Amniotic fluid will protect the embryo.

Front 3

Primitive Streak

Back 3

The point where epiblast cells have migrated towards the midline and then ingressed.

Front 4

First cells to ingress from the primitive streak

Back 4

Insert into and displace the hypoderm
Form the embryonic Endoderm

Front 5

Second set of cells to ingress through the primitive streak

Back 5

Insert between the hypo/endoderm and the epiderm layer to form the Mesoderm.

Front 6

The Notochord

Back 6

Formed by cells immediately migrating from the primitive node.
A transient embryonic structure that acts as a temporary spine for the embryo.
A center for signaling (by growth factors) to adjacent tissues.
Later integrated into spinal cord as the nucleus pulpus of the intervertebral disk

Front 7

Ectoderm

Back 7

Outer layer of skin (epidermis) and neural tissues.

Front 8

Mesoderm

Back 8

Skeletal and smooth muscle,
heart and blood vessels,
blood, bones, dermis of skin.
Supporting tissue between skin and gut tube.

Front 9

Endoderm

Back 9

Visceral organs, including gut tube, bladder, liver
pancreas and lungs.

Front 10

Summary of ICM development

Back 10

Front 11

Totipotent cells

Back 11

Can theoretically develop into any cell or tissue.
iPS = Induced Pluripotent stem cells
hESC = Human embryonic stem cells