Die Dynamik der Hautreaktion nach Hornschichtabri�

Ultrastructural studies of allergic contact dermatitis in man. Epidermal cell changes at 3, 6, and 12 h after application of DNCB

Early epidermal lesions of allergic contact dermatitis were examined by electron microscopy. Normal human volunteers were sensitized to DNCB, and contact reactions were elicited sequentially. Epidermal cell changes at 3 h included: the occurrence of small vacuoles with or without membrane, focal dilatation of intercellular spaces, and the alteration of tonofilaments into short, aggregated bundles. Non-sensitized skin to which DNCB was applied also showed small vacuoles with or without membrane. Monocytes infiltrated into the intercellular spaces which were not dilated, and the neighboring tonofilaments of keratinocytes remained normal.

Stereologic baseline data of normal human epidermis

Stereologic techniques for electron microscopic morphometry have been applied to normal human interfollicular epidermis of the submammary and iliac crest regions. The aim was to obtain objective baseline data for the study of epidermal morphometric pathology. The results, expressed mainly in surface, volume, and numerical densities of epidermal components and keratinocyte organelles, revealed ascending or descending gradients throughout the epithelial strata. The cytoplasmic ground substance remained almost constant in the four studied layers. No important regional differences were found between the epidermal morphometric parameters at either site. The epidermis showed striking volumetric composition similarities with other keratinizing epithelia.

Extracellular stimulation of epidermal DNA synthesis

The removal of the topmost cell layers of the epidermal stratum corneum by stripping initiates a series of biochemical events which alters the normal homeostatic control of and results in the acceleration of the cell cycle in basal cells which are ten to twenty cell layers removed from the site of stripping. One measure of accelerated events is a stimulation of thymidine incorporation into epidermal DNA at time intervals following stripping. Two peaks of maximal stimulation occur between 12 and 24 hr and 48 and 54 hr after stripping. Stimulation of thymidine incorporation into epidermal DNA by limited stripping is a useful technique for studying the stripping-initiated signal at the stratum corneum and its subsequent translation at the proliferative cell receptor site.

[Quantitative histometric investigations on the epidermis and corium of rat paw after experimental inflammation (author's transl)]

The epidermis and corium of rat right hind paw were investigated both histologically and histometrically after a subplantar injection of aerosil, formalin, carrageenin or Freund's complete adjuvant. The thickness of the epidermis and corium was determined on 5 rats respectively at 12 different times between 0.5 and 480 h post-treatment. Paw swelling was measured plethysmometrically on living rats. The left paw of untreated rats as well as the saline-injected and the untreated left paw of carrageenin-treated and adjuvant-treated animals respectively served as controls. Results 1. After the injection of the 4 substances, an acute inflammation developed maximally 4 to 24 h post-treatment in the corium. The thickness of the corium increased simultaneously with paw swelling. 2. Epidermal hyperplasia set in after a lag-phase of 12 h following the injection of formalin, carrageenin and adjuvant. 3. After injection of aerosil a subcutaneous oedema developed but no epidermal hyperplasia occured. 4. The formation of granulation tissue and necroses in the corium was seen only in the adjuvant-treated group 4 to 20 days post-treatment. At the same time, epidermal hyperplasia reached an absolute maximum. 5. The disturbance of nutrition and the lack of oxygen in the inflamed corium is possibly responsible for the initiation and persistence of the hyperplasia.

[Desmosomal structures in the cytoplasm of normal and abnormal keratinocytes (author's transl)]

The occurrence of intracytoplasmic desmosomes in normal, hyperplastic, and hyperkeratotic epithelia, in carcinoma-in-situ and in invasive carcinoma of the human oral cavity is demonstrated by electron microscopy. The mechanism for formation of these structures by invagination, separation and by intracytoplasmic incorporation of plasma membrane-desmosome-complexes are described in various oral epithelia, and other possible mechanisms are discussed. Intracytoplasmic desmosomes may occur in normal and pathological keratinocytes of all layers of the oral epithelium. Their ultrastructure in the peripheral cytoplasm is similar to that of the regular desmosomes on the cell surface. However, as they migrate centripetally, they show signs of degeneration, suggesting dissolution by lysosomal enzyme systems. Various surface membrane alterations involved in the formation of intracytoplasmic desmosomes may lead to a reduction of plasma membrane material and of desmosome structures and to defective intercellular adhesion. The intracytoplasmic incorporation of desmosome structures is a ubiquitous phenomenon exhibited by epithelial keratinocytes under certain physiological or pathological conditions.