Gradation of onset or rate of events in early development over the area for a physical substrate (e.g., initiating the making of connections starting in the front and finishing in the back of a structure). Also referred to as morphological gradients, the result is a series of progressively increasing and decreasing differences in the growth rate, metabolism, or physiological activity of cell, organ or organism. The process is governed by a variety of chemical signal molecules that act directly on the movement and development of cells during morphogenesis by forming a concentration gradient in the developmental tissue. Thus, they govern the pattern of tissue development and the positions of various specialized cells with a tissue. Following Alan Turing (1912-1954), the molecules are referred to as morphogens as first discussed in a seminal paper in 1952.
See Developmental gradients, Maturation, Maturational perspective/approach, Morphogenesis, Morphogenetic, Morphological field, Noggin, Polarizer, Skill learning hypothesis