Search

Previous studies from our laboratory suggested that architectural alterations of the cell membranes may have a major significance in the pathogenesis of psoriasis. Consequently, the membrane-bound Mg++ activated ATP-hydrolytic activity was investigated in normal and psoriatic epidermis under the electron microscope. The present study revealed that, in contrast to normal epidermis, only minimal ATP-hydrolytic activity is present on the cell membranes of psoriatic keratinocytes. This finding may reflect either a diminished attachment of substrate on the altered cell surface or an enzyme defect of the cell membrane a In both cases the reduced interaction between ATP and membrane-bound ATP-hydrolysing enzymes represents a functional membrane disorder of the psoriatic keratinocyte, presumably resulting in an insufficient utilization of ATP for active transport mechanisms on the cell surface. [ABSTRACT FROM AUTHOR]

Autonomic cutaneous nerves showing both agranular and dense core vesicles were found ending in the vicinity of smooth muscle cells (myoneural junctions). Sensory nerve preterminals contained numerous mitochondria, ending at the dermoepidermal interface either with or without Merkel cells (epithelioneural junctions), or in encapsulated organs in the dermis. No free epidermal or dermal endings were seen under the electron microscope. Although such endings may occur, it seems reasonable to suggest that contact zones rather than free axonal endings are the main pathways for skin innervation. Cytochemically, activity of nonspecific cholinesterases was demonstrated in numerous dermal axons and in pinocytotic vesicles in some cells of the vascular walls. Acetylcholinesterase activity was found limited to axons innervating smooth muscle and in pinocytotic vesicles of the smooth muscle cells. The periodic acid-silver methenamine (PASM) reaction revealed a thin layer of silver grains on the axolemma of nonmyelinated nerves, indicating the presence of glycoproteins at this level, whereas the axoplasm showed no affinity for silver before and after treatment with periodic acid. In specimens treated with alcian blue and lanthanum, a similar coat was seen occasionally on the axolemma of thin subepidermal nerves. The perineural sheath was a sufficient barrier for the penetration of lanthanum. In the axoplasm, abundant glycogen granules may be present, whereas no peroxidase or acid phosphatase activity was detected. [ABSTRACT FROM AUTHOR]

The structure of callus differs in many respects from that of normal human stratum corneum. This finding was confirmed both by scanning and transmission electron microscopy. Callous material consists of 2 types of horny cell as does normal stratum corneum. Both types, however, are thicker (5–8 μm) and extremely interdigitated as compared with normal horny cells. All intercellular spaces in callus are occupied by a dense cement material; signs of desquamation are therefore absent. After treatment with acid sodium thioglycolate (aNaThG) the dense matrix of callus keratin is reduced, the keratin framework of the horny cells is loosened and the characteristic α-keratin pattern can be observed. Moreover, most of the intercellular cement material is dissolved and some of the desmosomes are degraded. After aNaThG treatment and prolonged fixation in osmium, only the horny cell borders and a fibrillar skeleton remain. According to our findings, callus keratin is constructed similarly to the keratin of finger pad epidermis and of nail. The mode of keratinization in callus resembles that of hyperkeratosis by proliferation and not parakeratosis. Compared to nail keratin and the keratins of hair, however, callus keratin is less resistant to aNaThG. The high aNaThG-resistance of the horny cell border points to its function as a solid, stable container for keratins. [ABSTRACT FROM AUTHOR]

Copyright of Archiv für Dermatologische Forschung is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Archiv für Dermatologische Forschung is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Archiv für Dermatologische Forschung is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)