Inserts provide independent access to the basolateral and apical domains of polar cells, making applications such as transport studies, immunocytochemistry, electron microscopy, cell migration, and invasion possible. The track-etched polyethylene terephthalate (PET) membranes have individual cylindrical pores and are tissue culture treated. Cell culture on permeable supports results in greater morphological and/or physiological differentiation of many cell types. High density translucent membranes are recommended for transport studies. Transport membranes allow visualization of live cells by light microscopy. Inserts are supplied in sterile color-coded packaging.