Little is known about ciliogenesis as it proceeds through the entire airway tree, from the trachea to the terminal bronchioles, especially during the postnatal period. The purpose of this study was to define the spatial and temporal (prenatal and postnatal) pattern of normal cilia development in the mouse. Three airway generations representing the entire airway tree were examined: trachea, lobar bronchi, and terminal bronchiole. Ciliated cells in lung lobe whole mounts were labeled with a fluorescent dye for confocal microscopy, and ciliated cell surface density was measured for each airway generation and age. The same samples were examined by scanning electron microscopy to verify the appearance of ciliated cells among the differentiating epithelium of the airways. Ciliated cells were first detected in the trachea and lobar bronchi at 16 days gestational age (DGA) and in the terminal bronchioles at 18 DGA. Ciliated cell surface density increased with prenatal and postnatal age at all airway levels. However, the ciliated cell surface density of the trachea and lobar bronchi was always greater compared with the terminal bronchiole. In conclusion, the study revealed that in developing tracheobronchial airways of the mouse: 1) Ciliogenesis differs temporally and spatially by airway generation; 2) Ciliated cell surface density increases with age in all airway generations, but density decreases in a proximal to distal direction; and 3) A significant portion of ciliogenesis continues after birth. This study provides a healthy basis for investigations of neonatal pulmonary disease or pollutant toxicity affecting cilia and its functions.

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The CPLEAR collaboration has constructed a detector at CERN for an extensive programme of CP-, T-and CPT-symmetry studies using K and K 0 produced by the annihilation of p's in a hydrogen gas target. The K 0 and K 0 are identi ed by their companion products of the annihilation K which are tracked with multiwire proportional chambers, drift chambers and streamer tubes. Particle identi cation is carried out with a liquid Cherenkov detector for fast separation of pions and kaons and with scintillators which a l l o w the measurement o f t i m e o f i g h t and energy loss. Photons are measured with a lead/gas sampling electromagnetic calorimeter. The required antiproton annihilation modes are selected by fast online processors using the tracking chamber and particle identi cation information. All the detectors are mounted in a 0.44 T uniform eld of an axial solenoid of diameter 2 m and length 3.6 m to form a magnetic spectrometer capable of full online reconstruction and selection of events. The design, operating parameters and performance of the sub-detectors are described.

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