morphogenn.

1952 A. M. Turing in Philos. Trans. (Royal Soc.) B. 237 38 The systems actually to be considered consist therefore of masses of tissues which are not growing, but within which certain substances are reacting chemically, and through which they are diffusing. These substances will be called morphogens, the word being intended to convey the idea of a form producer. It is not intended to have any very exact meaning.

1965 Math. in Biol. & Med. (Med. Res. Council) vi. 247 Turing considers the behaviour of two chemical substances, A and B, which he calls ‘morphogens’. The significance of the name is simply that it is supposed that a high concentration of one or other of these substances can act as an ‘inducer’ of further differentiation.

1972 Nature 13 Oct. 366/1 Many theories for the mechanism of signalling in embryos have been produced; the oldest, and simplest, is that there is a concentration gradient of a ‘morphogen’ from the animal to vegetal poles, and that cells can measure their ambient concentration and then behave according to their position in the gradient.

1988 Sci. Amer. Mar. 62/3 The existence of morphogens is still largely speculative.

1994 N.Y. Times 11 Jan. c1/4 The morphogen tells the cells it touches where they are situated in the body and what they are destined to become. It gives them their address, their fate, their identity, their purpose in life.