Scanning electron microscopic observations of the human respiratory tract
M. F. Greenwood and P. Holland
As viewed by scanning electron microscopy, the luminal surface of the human
trachea at 12 weeks' gestation shows a predominance of
microvillous-covered, nonciliated cells, in contrast to the heavily
ciliated tracheobronchial surface seen at 34 weeks' gestation. Hyaline
membrane disease produces a confluent lining material in the lung periphery
that obscures the bronchiolar and alveolar surface architecture. Large
saucer-shaped alveoli, numerous alveolar pores, and an abundance of in situ
alveolar macrophages are observed in chronic bronchitis and in
emphysematous lungs; The scanning electron microscope offers an additional
tool for the study of developmental and pathological processes in the human
respiratory tract.
