منابع مشابه
The interpretation of morphogen gradients.
Morphogens act as graded positional cues that control cell fate specification in many developing tissues. This concept, in which a signalling gradient regulates differential gene expression in a concentration-dependent manner, provides a basis for understanding many patterning processes. It also raises several mechanistic issues, such as how responding cells perceive and interpret the concentra...
متن کاملScaling of morphogen gradients.
Individuals of the same or closely related species can vary substantially in size. Still, the proportions within and between tissues are precisely kept. This adaptation of pattern with size termed scaling, is receiving a growing attention. We review experimental evidence for scaling, and describe theoretical models for mechanisms that scale morphogen gradients. We particularly note the Expansio...
متن کاملShaping Morphogen Gradients
Shh activity and at different distances from the source. The proper functioning of tissues and organs requires These observations provide unequivocal evidence that that each cell differentiate appropriately for its position. Shh acts directly on distant cells and therefore that Shh In many cases, the positional information that instructs forms a morphogen gradient in the developing neural cells...
متن کاملLocal kinetics of morphogen gradients.
Some aspects of pattern formation in developing embryos can be described by nonlinear reaction-diffusion equations. An important class of these models accounts for diffusion and degradation of a locally produced single chemical species. At long times, solutions of such models approach a steady state in which the concentration decays with distance from the source of production. We present analyt...
متن کاملRobust formation of morphogen gradients.
We discuss the formation of graded morphogen profiles in a cell layer by nonlinear transport phenomena, important for patterning developing organisms. We focus on a process termed transcytosis, where morphogen transport results from the binding of ligands to receptors on the cell surface, incorporation into the cell, and subsequent externalization. Starting from a microscopic model, we derive e...
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ژورنال
عنوان ژورنال: Development
سال: 2006
ISSN: 1477-9129,0950-1991
DOI: 10.1242/dev.02238