Abstract: An insert for trans-membrane co-culture includes a hollow housing with a passageway therethrough, a first end, a second end and a center section intermediate the first and second end. The passageway has an inside diameter at the first end and the second end that is larger than the inside diameter of the passageway at the center section so that the passageway tapers from each end to the center section. The center section includes a porous membrane having a first surface and a second surface attached across and obstructing the passageway. The membrane forms a first receptacle from the passageway toward the first end and forms a second receptacle from the passageway toward the second end. A method for using the insert of the present invention to grow cells on both sides of a porous membrane includes horizontally submerging the insert in liquid medium so that the air in the receptacles is displaced by the medium.