Set-up for in vivo microscopy of the ventilated rat lung. A: After placement of a catheter central to the heart through the right carotid artery, a tracheostomy and canulation of the trachea was performed for establishing mechanical ventilation. The chest wall was removed and the right lower lobe was exposed. B: A glass cover slip, mounted on a specially designed holding device, was placed upon the right lower lobe with minimal pressure to serve as artificial pleura, and the animal was placed under an upright in vivo microscope. Time frame (10 sec.) of stably adherent and sticking human colon cancer cell. C: Full scale microscopic pictures representative for in vivo microscopy of the ventilated and physiologically perfused lung in-situ. The presented pictures were taken at the indicated time intervals after tumor cell injection. One fluorescence-labeled cell is stably adherent to the vascular wall over the 10 second interval of observation. The other cell ("sticking cell") is adherent for a few seconds to the wall without establishing stable adhesion and finally recirculates through the pulmonary capillaries. For quantitative analysis of tumor cell adhesion, the lung surface was screened for stably adherent cells in a standardized fashion in 10 minute intervals for a total of 40 minutes.