Latest Hans Spemann Stories
How is it that a disc-like cluster of cells transforms within the first month of pregnancy into an elongated embryo?
More than 80 years have passed since the German scientist Hans Spemann conducted his famous experiment that laid the foundations for the field of embryonic development. After dividing a salamander embryo in half, Spemann noticed that one half â€“ specifically, the half that gives rise to the salamander's 'belly' (ventral) starts to wither away.
- A pivoted catch designed to fall into a notch on a ratchet wheel so as to allow movement in only one direction (e.g. on a windlass or in a clock mechanism), or alternatively to move the wheel in one direction.