For decades, scientists have intensively studied this process, called morphogenesis, but it remains in many ways enigmatic.
Adhesion code
Three genes—N-cadherin, cadherin 11 and protocadherin 19—emerged as essential for normal patterning. The expression of different combinations and different levels of these genes was responsible for differences in adhesion preference, representing what the team dubbed an adhesion code. This code was unique to each of the cell types and determined which other cells each cell type stays connected to during morphogenesis.
Common Design 