New views on the construction of human gingival epithelium

The effects on the basal and spinous layers of human keratinized oral epithelium of 2 glutaraldehyde-based fixatives with buffers hypoosmolar and isoosmolar to blood, respectively, have been investigated. The first-mentioned solution produced an electron microscopic image corresponding to the classical view, that is an epithelium consisting of closely-packed cells having short and stubby membrane projections and separated by an extremely narrow intercellular space. In the Langerhans cells, the specific granules appeared racket-shaped and had a unilaminar limiting membrane with a periodic structure along its internal face. There are strong reasons to believe that these morphological characteristics are swelling artifacts. The last-mentioned fixative produced keratinocytes provided with numerous microvilli and membrane ruffles and disk-shaped Langerhans cell granules surrounded by a trilaminar membrane. Concomitantly, the intercellular space appears very wide and there is evidence for the view that this is a more realistic picture of the in vivo situation and not a gross distortion caused by shrinking during the tissue processing. Broad interstices can explain certain basic events as rapid cell motility within the epithelium and offer efficient pathways for rapid transport of substances.