Chemical developments

摘要

How does the human newborn-composed of approximately one trillion cells and over 200 cell types-arise from a single, fertilised egg? Since the time of Aristotle, scientists have strived to explain this fascinating transformation, using a perturb-and-observe approach to study model organisms. These pioneering developmental biologists examined embryos from sea urchins, chickens, frogs, and other animals, using dyes to follow cell lineages and surgical procedures to study interactions between tissues. Their investigations revealed conserved embryological processes among evolutionarily diverse organisms and introduced concepts such as morphogen gradients - gradients of cell signalling molecules that influence tissue growth patterns.