The ultrastructure of the human antral mucosa as demonstrated by freeze-fracturing.

The fine structure of the normal mucous membrane in the human maxillary sinus was investigated by means of the freeze-fracture technique. Special interest was directed to membrane structures in the epithelial cells. The morphology of tight junctions could be analysed. According to morphological criteria these junctions might be classified as "very tight". So called ciliary necklaces were well distinguishable. Their morphology seemed to be in concordance with the structure reported in other mammalian respiratory epithelia. Abluminally the epithelial cells frequently displayed abundant caveolae or micropinocytotic vesicles. The present investigation was performed as a preface to later studies on pathologically altered antral mucosa.