For studying diseases, such as chronic obstructive pulmonary disease (COPD), cells are often grown in air liquid interface.
I understand that the common way of establishing this these days is to grow cells in culture well inserts with a permeable bottom, then put medium only in the well and not the insert.
Here is an image from Stemcell Technologies:
The last images implies that the level of the medium is just high enough to cover only the basal side of cells. Is this realistic? Given that the monolayer is a few microns thick, is it really just a matter of carefully pipetting just enough medium? It seems like the error of a pipette is too high for this.
In practice, I am getting the impression that the level of liquid is actually higher than the apical surface of the cells, but it is somehow prevented from seeping out of the well and into the insert. If so, how? The bottom of the insert is permeable; even if you grow cells to confluence, surely there will be a small hole or two somewhere which causes a leak?