This proposal plans to: 1) use and appropriately modify the dual-rotary circumfusion system technique for the culturing of lung tissue explants the maintenance of their tissue integrity for protracted periods of time; 2) study these histotypic cultures for their normal cellular activities by time-lapse procedures and for their ultrastructural changes; and 3) elicit the living culture's response, as well as detect ultrastructural responses, to physical, biological, and pharmacological alterations to the in vitro microenvironments.