| Creode: Paradigm used by Waddington (1905-1975) in his description of epigenetic landscape. Creodes illustrate developmental pathways followed by cells as they proliferate and differentiate into organs [63,67]. |
| Epigenetic landscape: Concept imagined by Waddington, within which cells are represented by spheres rolling down in a landscape into deep and narrow valleys (canalization or fate determination, which cannot be escaped), until reaching a stable state. Changes of states are prevented by ridges (or energy barriers) that do not allow movement from one stable state (valley) to another one. Creodes materialize the trajectory of cells, in a succession of expression patterns. Waddington's epigenetic landscape also provided a metaphor for how development might be modulated [68]. |
| Genocentrism: Neologism derived from the adjective, genocentric, to emphasize the overwhelming role taken by gene in cellular processes. Genocentrism at its climax would restraint any phenomenon under the exclusive control of genes. |
| Homunculus: Miniature human, integrally formed, also called animalcules, which is within eggs (ovist theory) or spermatozoon (spermist theory), according to preformationist theories. Organisms are preformed and embryogenesis is restrained to successive growth periods [69]. |
| Self-organization: Emergence from an initially disordered system of a dynamic organization. The latter arises from the collective behavior of components, where the individual properties of the component cannot account for the final dynamic pattern. Thus, an organization in space and time leads to emergent properties, whose characteristics are qualitatively different from the components. Self-organization is considered as a dissipative phenomenon. |
| Spemann organizer: The concept of induction in developmental biology. In amphibian, it refers to a group of cells, positioned at dorsal lip of the blastopore, which induces the development of the neural tissue. Initially discovered by Hans Spemann and Hilde Mangold (1898-1924) in amphibian, this primary organizer is now admitted to exist in many animal models. This primary organizer is set up by the Nieuwkoop Center, which is the dorsal- and vegetal-most cell of the early amphibian blastula. |
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