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Dermal-epidermal Junction (dermal-epidermal + junction)
Selected AbstractsPredominant formation of heavily pigmented dermal melanocytomas resembling ,animal-type' melanomas in hepatocyte growth factor (C57BL/6 × C3H)F1 mice following neonatal UV irradiationJOURNAL OF CUTANEOUS PATHOLOGY, Issue 9 2007Scott R. Florell Background:, Transgenic mice expressing hepatocyte growth factor (HGF) develop cutaneous melanocytic tumors following neonatal UV exposure. Here, we examined the histologic spectrum of UV-induced melanocytic tumors in HGF mice on a pigmented (C57BL/6 × C3H/HeN)F1 background. Methods:, Neonatally irradiated (4000 J/m2) mice were monitored for 43 weeks, and 31/34 (91%) animals developed a total of 163 melanocytic tumors. Results:, Of 54 primary tumors analyzed, most (49/54, 91%) demonstrated exclusively dermal collections of epithelioid cells with voluminous densely pigmented cytoplasm. Seven of these also demonstrated a population of spindled cells with mitoses. Several (3/54, 6%) tumors exhibited a junctional component with melanocytes present in the epidermis. Staining with PEP8 confirmed the presence of interfollicular melanocytes at the dermal-epidermal junction in neonatal skin. Conclusions:, In contrast to HGF animals on an albino (FVB) background, HGF animals on the pigmented (C57BL/6 × C3H/HeN)F1 background do not develop classic radial growth phase melanoma but rather predominantly develop dermal melanocytomas resembling the ,animal-type' melanoma occasionally seen in humans. These results demonstrate the influence of genetic background on histologic pattern of UV-induced melanomas in mice. [source] The inflammatory response in drug-induced acute urticaria: ultrastructural study of the dermal microvascular unitJOURNAL OF THE EUROPEAN ACADEMY OF DERMATOLOGY & VENEREOLOGY, Issue 9 2006PR Criado Abstract Background, Drug exposure is one of the main aetiologies of urticaria and represents the second most common cause in acute urticarias. Studies involving the ultrastructural aspects of urticaria are relatively rare in the literature. Most of the articles published report on skin biopsies of experimentally induced urticaria, and acute urticaria has been studied even less from a morphological point of view. Objectives, The aims of this study were to observe ultrastructural cell characteristics in five patients with drug-induced acute urticaria and possible aspects of the inflammatory skin response. Methods, Clinical manifestations, light microscopy and transmission electron microscopy were evaluated. Results, With light microscopy, a mild perivascular lymphocyte-monocyte infiltrate was observed with few neutrophils and dermal oedema in skin biopsies of five patients. With electron microscopy, a mild vascular dilatation was observed, with platelets in the lumen and several lymphocytes and dendritic cells close to the superficial dermal vessels. Some mast cells appeared normal, whereas others were granule-depleted. In some areas, mast cells, lymphocytes and satellite dendritic cells were closely associated, as well as some macrophages. A significant number of plasma cells, eosinophils and polymorphonuclear neutrophils were not observed; however, the presence of lymphocytes and macrophages was significant. The epidermis and the dermal-epidermal junction were preserved, except for a discrete oedema in keratinocytes. Conclusions, The ultrastructural aspect of drug-induced acute urticaria is similar to that observed in urticaria caused by Urtica dioica, intradermal histamine and cold urticaria. The presence of the cellular triad with mast cells, dendritic (or satellite) cells and lymphocytes suggests a functional interaction of these cells. These findings support the possible existence of mechanisms in the dermis that may participate in protective and/or injurious vasocentric immune reactions. [source] Novel Aspects of Intrinsic and Extrinsic Aging of Human Skin: Beneficial Effects of Soy Extract,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2005Kirstin M. Südel ABSTRACT Biochemical and structural changes of dermal connective tissue substantially contribute to the phenotype of aging skin. To study connective tissue metabolism with respect to ultraviolet (UV) exposure, we performed an in vitro (human dermal fibroblasts) and an in vivo complementary DNA array study in combination with protein analysis in young and old volunteers. Several genes of the collagen metabolism such as Collagen I, III and VI as well as heat shock protein 47 and matrix metalloproteinase-1 are expressed differentially, indicating UV-mediated effects on collagen expression, processing and degradation. In particular, Collagen I is time and age dependently reduced after a single UV exposure in human skin in vivo. Moreover, older subjects display a lower baseline level and a shorter UV-mediated increase in hyaluronan (HA) levels. To counteract these age-dependent changes, cultured fibroblasts were treated with a specific soy extract. This treatment resulted in increased collagen and HA synthesis. In a placebo-controlled in vivo study, topical application of an isoflavone-containing emulsion significantly enhanced the number of dermal papillae per area after 2 weeks. Because the flattening of the dermal-epidermal junction is the most reproducible structural change in aged skin, this soy extract appears to rejuvenate the structure of mature skin. [source] Distribution of P2X3 -immunoreactive fibers in hairy and glabrous skin of the ratTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 6 2009Anna M.W. Taylor Abstract The skin is innervated by two populations of unmyelinated sensory fibers, the peptidergic and nonpeptidergic, which transmit nociceptive information to the central nervous system. The peptidergic population expresses neuropeptides such as substance P (SP) and calcitonin gene-related peptide (CGRP) and has both cutaneous and visceral targets. The nonpeptidergic population expresses the purinergic receptor P2X3, binds the isolectin B4 (IB4), and innervates mainly the epidermis. To date, the peptidergic nociceptor population in cutaneous tissue of the rat has been well characterized, whereas the nonpeptidergic innervation pattern has lacked an adequate description. To this aim, we used light microscopic immunocytochemistry to investigate the pattern of P2X3 -immunoreactive (-IR) fiber innervation of both hairy and glabrous skin from male Sprague-Dawley rats. Our results show extensive P2X3 -IR fibers throughout the upper and lower dermis. Thick bundles of P2X3 -IR fibers were found to run in parallel with the dermal-epidermal junction and projected multiple thin collateral axons that penetrated the epidermal layer, creating a dense network of innervation throughout the entire epidermis. The distribution of P2X3 -IR fibers in the epidermis was far more extensive than the distribution of CGRP-IR fibers. P2X3 -IR fibers also innervate hair follicles but were rarely found in close proximity to glands and blood vessels. The present results suggest a primary role for P2X3 -IR fibers in the detection of noxious stimuli in cutaneous tissue and provide an anatomical basis for future studies examining a possible functionally distinct role of nonpeptidergic nociceptors in the transmission of nociceptive signals. J. Comp. Neurol. 514:555,566, 2009. © 2009 Wiley-Liss, Inc. [source] | |||||||||||||