[mass noun] The theory, now generally held, that an embryo develops progressively from an undifferentiated egg cell.Often contrasted with preformation
- ‘Chapter 5 introduces their role in development, concluding that epigenesis is really, really complicated.’
- ‘The contrary view to epigenesis, namely that the embryo was preformed from the beginning, was championed anew in the late 17th century.’
- ‘He did not assume that an inert and common matter was sufficient for a plausible formulation of a theory of mechanical epigenesis.’
- ‘In epigenesis, the developing organism begins in an undifferentiated state and gradually changes to a more complex state through multiple interactions.’
- ‘But while the wholesale conversion to epigenesis put an end to fictitious accounts of miniature organisms, it brought biologists face to face once again with the old question of how the egg gave rise to a fully formed organism.’
Mid 17th century: from epi- ‘in addition’+ genesis.