Previews rendered with vray (materials included). I would recommend viewing the higher resolution renders as a lot of the fine detail is lost in the 400x400 px previews.
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 in ver. 2008).
Other microbiology models available (or will be soon) - DNA model, chromosome, mitochondrium, plant cell etc.
For the 3dsMax version with standard materials the peroxisomes are a single mesh and in the version with vray shaders these are a particle cloud so you can add a spawn movment for animations. Depending on your individual needs you can merge the desired object. Works with Max 9, 2008 and 2009. Also 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.