Computer-assisted image analysis of skin surface replicas

Using a rubber-based dental impression material, negative surface impressions were made of demarcated areas of skin and prepared as dry specimens for scanning-electron microscopy. Electron micrographs were taken at low magnification and, using a programmed computer-assisted image analyser, it was possible to represent quantitatively the topography of that particular body site according to the degree of circularity of the various geometric subunits. This technique was most applicable to skin topography with a reliable geometrical pattern of triangles and squares, a feature of hair-bearing surfaces in general and in particular, the antecubital fossa. Using standardized trauma of various types the origin of skin surface markings were found to be located in the dermis. The technique was applied to the healing of experimental trauma produced by tape stripping, the resolution of clinical eczema and a comparison of steroid-treated and untreated tape-stripped skin.     

Lysosomal hydrolases of the epidermis

The activity of twelve acid hydrolases has been measured in serial horizontal sections of cow snout epidermis. The majority of these enzymes showed a clear peak in the basal and lower spinous cell layers; acid phosphatase, however, was found mainly in the keratinizing zone. These findings suggest that two discrete populations of lysosomes may occur in epidermis. Those present in the lower layers possess a typical pattern of hydrolase activity and probably correspond to the 'orthodox' lysosomes observed by electron microscopy techniques, whereas those found in the keratinizing zone possess an unusual hydrolase profile and may correspond to the bodies identified morphologically as keratinosomes (Odland bodies, membrane-coating granules).