Embryonic Development.
- During Gastrulation:
The embryo contains 3 different layers
* ectoderm; outside
* endoderm; inside
* mesoderm; middle
These layers will develop into specialized organs and area
* ectoderm; skin, brain, spinal cord, all neuron,
sensory receptors
* endoderm; lining of gut, lung, bladder, liver,
pancreas
* mesoderm; notochord, muscles, blood, bone, sex
organ