Morphogenesis: How Cells Shape Embryonic Development

Scientists have been trying to figure out how a simple fertilized egg turns into a complex and diverse organism with different types of cells, like neurons and bone cells. This process is called morphogenesis and it determines how cells are arranged in space during embryonic development, which shapes the overall body plan.

The "French flag model" explains cell distribution during embryonic development. A poster from 1916 shows children with toys and the flag saluting injured soldiers on Bastille Day.

In the early 1900s, a scientist named Thomas Hunt Morgan observed that worms could regenerate different body parts at different rates and in different places. He suggested that cells send signals to each other to organize and differentiate, creating specialized cells like neurons or bone cells.

Years later, a scientist named Alan Turing proposed that chemicals called morphogens help to organize cells into specific patterns based on their concentration. Another scientist, Lewis Wolpert, developed the "French flag model" to explain this idea. In this model, cells closest to the source of the morphogen (represented by the blue part of the flag) would receive the highest concentration, activating certain genes that lead to different cell types. Cells farther from the source (white and red parts of the flag) would receive lower concentrations of the morphogen, leading to different patterns of gene activation.

Using this model, scientists like Christiane Nüsslein-Volhard were able to determine the genetic basis for the body plan of fruit flies. Their work helped us better understand how cells organize themselves during development to create complex and diverse organisms.