Morphogen

A signaling molecule whose concentration helps specify different cell fates across a developing tissue. Cells interpret its spatial distribution through concentration-dependent responses.

Morphogen gradient: A spatial distribution of morphogen concentration across a tissue. Different positions in this gradient expose cells to different signal levels.
Drosophila melanogaster: A fruit fly widely used as a model organism in genetics and developmental biology. Its early embryo revealed how maternal signals establish concentration-dependent gene-expression domains.
Cell differentiation: The process by which a cell acquires specialized structures and functions. Morphogen exposure helps guide which differentiated identity a developing cell adopts.
Lewis Wolpert: A British developmental biologist known for proposing the French flag model of positional information. His model gave a clear framework for explaining how gradients specify tissue patterns.
Morphogen transport: The movement of signaling molecules through and between cells in a tissue. Transport routes and rates help determine the shape and reach of a morphogen gradient.
Threshold response: A response that begins or changes when a measured quantity crosses a particular level. Cells can adopt different fates when morphogen concentration crosses distinct thresholds.
Bicoid: A Drosophila transcription factor distributed in a concentration gradient along the early embryo. Its gradient helps specify anterior structures and is a classic morphogen example.
Embryonic development: The process by which an embryo grows and forms organized tissues and organs. Morphogen gradients operate within developing tissues as their spatial organization emerges.
Positional information: Information about a cell's location that helps determine its developmental fate. Morphogen gradients are a proposed means by which cells acquire positional information.
Morphogen degradation: The breakdown or removal of a signaling molecule from a biological system. Degradation helps set gradient range and can change the duration of cellular exposure.

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