File:Waddington1956 fig1.4.jpg
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Figure 1.4 The development of a district of competence into an individuation field
The diagrams show a longitudinal section through a region of a developing embryo. At the earliest stage (1) the precursor (A) of a certain organ has not yet reached the threshold anywhere; this is the stage of a ‘district of competence’.
In (2) the concentration of the active substance A has reached the threshold and an individuation field for the organ is beginning to arise.
In (3) the individuation field extends outside the area in which the organ will actually appear, which is dotted. The peripheral parts of the individuation field depress the level of A. This is the stage which persists in lower forms in which regeneration is possible. In (4) the individuation field has contracted until it is confined to the area of the developing organ; meanwhile the substance A has disappeared in the outer parts of the region, partly owing to the suppressive action of the individuation field and partly as a simple result of the progress of development.
Reference
Waddington CH. Principles of Embryology (1956) The MacMillan Co., New York
Cite this page: Hill, M.A. (2024, April 19) Embryology Waddington1956 fig1.4.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Waddington1956_fig1.4.jpg
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
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