01
Zygote
Day 0 to 1
One cell holds the whole plan.
Follow a single cell as it builds a whole body. Each panel names the force doing the most work at that step. The pictures are schematic diagrams, not photographs.
One cell holds the whole plan.
Cells divide but the ball does not grow yet. The first cells specialize, and the first cells die (quality-control death in the inner cell mass).
Signals build the three layers of the body. True growth finally begins.
Signals draw the body plan. The neural tube folds shut, mostly by cells squeezing and folding, and the hand begins to be carved.
The same genome branches at once into heart, brain, skin, bone, limb, and face. Each cell reads the same signals differently.
Fingers appear because the cells between them die. Ducks keep their webbing by switching that death off.
Matrix is built by dehydration synthesis and reshaped by hydrolysis. Building and breaking are partners.
Now the body truly scales up, adding cells and size until birth.
These are schematic diagrams that teach the idea. Real tissue photographs of each stage, in mouse and human, are a planned next step and will be added only from openly licensed sources, credited, and cleared before posting. No tissue image is ever generated or faked.