Identification of the epidermal barrier: a comprative histological study using different techniques

ABSTRACT

The present study has been undertaken to re-evaluate the site responsible for the low permeability of skin. Utilization of transmission electron microscopy and electron-dense tracer technique has made it possible to show that all the intercellular spaces of the stratum basale, stratum spinosum, stratum granulosum and, more significantly, the intercellular space between the superficial granular and basal corneal layers of the epidermis are permeated by Lanthanum. In the granular-corneal interface dense deposits of lanthanum and aggregations of excreted contents of lamellar bodies are observed. However, no lanthanum has entered the intercellular spaces of the stratum corneum. The present study suggests that the stratum granulosum and the granular-corneal interface do not function as an effective barrier to the passage of water-soluble intercellular tracers. It is concluded that the intercellular substance in the entire stratum corneum provides or forms "Physiological" tight junctions which impede the movement of water-soluble intercellular tracers and, more significantly, to transepidermal water loss