Interactions during cell adhesion to external surfaces may reach the l
evel of discrimination of molecular chirality. Cultured epithelial cel
ls interact differently with the {011} faces of the (R,R) and (S,S) ca
lcium tartrate tetrahydrate crystals. In a modified version of the cla
ssical Pasteur experiment, the enantiomorphous crystals were sorted ou
t from a 1:1 mixture by the selective adhesion of cells to the (R,R) c
rystals. This stereospecificity results from molecular recognition bet
ween chiral components on the cell surface and the structured crystal
surface. Crystals may allow experimental differentiation between disti
nct stages in cell substrate contacts, providing mechanistic informati
on not readily attainable on conventional heterogeneous surfaces.