One disease afflicting these structures can be determined by detecting anti-GM-CSF autoantibodies in BAL fluid samples. The formation of tubular myelin into the hypophase layer of these structures occurs following the exocytosis of lamellar bodies. Pathogens invading these structures are marked for phagocytosis and opsonized by SP-A and SP-D. A substance produced by these structures is mainly made of (15[1]) phosphatidylcholines, (10[2]-5[1])including (*) DPPC. That substance is secreted into the atrium of these structures (10[1])by type II cells to reduce surface tension. The walls of capillaries and these structures form blood-air barriers permeable to carbon dioxide and oxygen. For 10 points, gas exchange is facilitated by what small air sacs found in the (10[2]0[1])lungs? ■END■