What term describes a molecule present in a concentration gradient that specifies the fate of each cell along the gradient?

The term that describes a molecule present in a concentration gradient which influences the fate of each cell along that gradient is "morphogen." Morphogens are signaling molecules that provide positional information, contributing to the process of development and differentiation in organisms. They typically form gradients, in which the concentration of the morphogen varies, allowing cells at different locations to receive varying signals. This variation can trigger distinct developmental pathways, guiding cells to adopt specific identities and functions based on their position relative to the morphogen source.

Understanding morphogens is crucial in developmental biology, as they are involved in processes such as tissue patterning and orchestrating the spatial organization of cells during embryonic development. Their role is foundational to the fields of embryology and regenerative biology, where the precise control of cell fate is essential for proper development and healing.