ABSTRACT
The process of development of the embryo has inspired philosophical speculation since the advent of Western thought. Since the time of Aristotle two antithetical conceptual models have traditionally been used to understand embryogenesis: either form or structure is preformed in the embryo or it is newly formed with each generation. Our aim in this article is to show that the contrast between the pre-formationist and epigenetic positions persists despite the formidable theoretical and experimental advances of contemporary developmental biology. Pre-formationism and epigenesis have constantly refined their positions in the course of history in order to answer the conceptual challenges of each epoch. This process of continuous transformation has resulted in a partial convergence of the two positions. However, we shall argue that, despite the partial successes of this process of continuous convergence, one of the most fundamental antinomies in biology persists.
KEYWORDS:
Embryo; Pre-formationism; Epigenesis; Determinant; Morphogenetic field; Morphogen; Regulation