Assessment of particle retention and clearance in the intrapulmonary conducting airways of hamster lungs with the fractionator.
A modified version of the fractionator was used to estimate the total number of polystyrene microspheres retained in the airways of hamster lungs at two different time points after inhalation. A systematic three-stage subsampling procedure with known sampling fractions was adopted. First, each lung was cut into slices, from which primary disectors were sampled systematically with a known sampling fraction. From each primary disector, smaller sub-disectors were subsampled, and the corresponding sampling fraction was estimated by point counting. Finally, a few particles were counted at the microscopic level in the sub-disectors, and the final estimate of total particle number (which is unbiased irrespective of any tissue deformations) was easily computed as a product of the counted number times the reciprocal of the successive sampling fractions. The error variance of each estimate was assessed from the data using a new estimator. An average of 6% of the deposited particles were retained on the epithelial surface of the intrapulmonary conducting airways shortly after the inhalation, from which at least one-third was already phagocytosed by macrophages. After 24 h, an average of 87% of the particles retained shortly after the inhalation had been cleared. The proportion of particles ingested by macrophages had increased to at least 87% in three out of four animals studied.
Geiser
M
M
Department of Anatomy, University of Berne, Switzerland.
Cruz-Orive
L M
LM
Im Hof
V
V
Gehr
P
P
D000818:Animals; D005591:Chemical Fractionation; D006224:Cricetinae; D008168:Lung / Q000502:physiology*; D008264:Macrophages / Q000502:physiology*; D008297:Male; D008433:Mathematics; D008647:Mesocricetus; D008863:Microspheres; D009079:Mucociliary Clearance / Q000502:physiology*