3ds Max version with standard materials or vray shaders. Other formats available - fbx, obj, Maya .ma (only geometry), 3ds (some parts will need additional subdivision due to the limitations of the 3ds format) all exported from 3dsMax (except the .ma saved in ver. 2008).
Other microbiology models available (or will be soon) - DNA model, chromosome, mitochondrium, plant cell etc.
(!) Note that although I try to set everything up in the scene to minimize errors, limitations of individual file formats might require welding vertices, fixing smoothing groups or fliping normals for some objects after importing geometry.