Ontogeny recapitulates phylogeny. An observation that a human’s developing embryo goes through stages appearing to be similar to stages in our evolutionary history.
Early on we look like some very early chordates (sort of worm like). [and of course men never grow out of this stage :-) ] Then we look like fish (we even have gills), amphibians, lizards. At later stages we look incredibly like a young chicken. That is so cool, and it just happens to be what our embryos looks like, at least to some, and me too.
But it got me wondering whether the molecular and cellular connections that cause a human embryo to look like an amphibian might be similar enough that they would be sensitive to the chemicals that affect an amphibian or its development. Such as…. http://www.kcet.org/news/redefine/rewild/amphibians-1/central-valley-wildlife-refuges-are-deformed-frog-hotspots.html Hmmmmmmmmmmmmm