This is the lining tissue of most of the conducting portion of the
respiratory tract. The lumen (apical surface) is up in this picture. Notice
the narrow columnar cells and the prominent basement membrane (solid pink
line). ALL the cells attach to this membrane, though not all reach the
apical surface. Since the nuclei are not all at the same level, the tissue
appears to be stratified, even though it is not; hence the term 'pseudostratified.'
Notice also the occasional goblet cells, and the cilia which line the apical
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