If pressure from outside the lungs causes atelectasis, your doctor will treat the cause of the pressure. For example, if the cause is a tumor or fluid buildup, your doctor will remove the tumor or fluid. This will allow your lung to fully expand. Atelectasis Caused by a Blockage
Pilus. Definition. noun, plural: pili. (microbiology) Short, filamentous projection on a bacterial cell, used not for motility but for adhering to other bacterial cell (especially for mating) or to animal cells. Supplement. Bacterial pili are involved in cell adhesion.
1 Cell Wall â lends to the shape of the cell; two types are gram positive and gram negative.  Pili â hair-like projections surrounding the outer layer of the cell; enables bacteria to stick-on surfaces or latch-on other cells.