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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The transparency of the homozygous hairless mouse ear permits detailed study of the intact skin microcirculation without surgical interventions to the skin tissue. It is useful to study many microvascular phenomena and has the potential to provide data to clarify issues related to human skin microcirculation. The aim of this investigation was to quantify the normal capillary geometric and hemodynamic parameters. In each of 36 capillary pairs (10 mice), capillary diameter (D), length (L), and velocity (V) were measured and blood flow (Q) and shear rate (S = 8V/D) were calculated. Loops were chosen such that each branch of the capillary pair had a common arteriolar origin, venule confluence, and thus a common pressure difference across each branch, thereby eliminating the confounding effects of these variables on perfusion differences in each of the branches. Temporal and overall distributions for each parameter were determined and comparisons between paired capillaries made. Overall mean +/- SEM were for D, L, V, Q, and S, respectively, 4.8 +/- 0.2 microns, 161 +/- 5 microns, 192 +/- 5 microns/sec, 3.6 +/- 0.3 pl/sec, and 43 +/- 3 sec-1. Symmetry between paired capillaries was assessed by parameter ratios (smaller/larger); for D, V, Q, and S, respectively, these were 0.85 +/- 0.02, 0.66 +/- 0.03, 0.60 +/- 0.04, and 0.64 +/- 0.04 with corresponding distribution medians of 0.86, 0.72, 0.63, and 0.64. Similar comparisons were made for parameters in smaller/larger diameter capillary pairs yielding for V, Q and S; 1.14 +/- 0.12, 0.82 +/- 0.09, and 1.37 +/- 0.14 with corresponding medians of 0.9, 1.07, and 0.69. These composite results provide baseline data on the naturally occurring animal-to-animal variability, temporal variation, and overall parameter value distributions in the capillary network of this experimental model of skin microcirculation. They thus provide the necessary initial framework for subsequent assessments of pharmacological interventions and the study of various pathological processes on capillary perfusion parameters.
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PMID:Skin capillary metrics and hemodynamics in the hairless mouse. 160 39

The denuded basal cell layer of the hairless mouse epidermis is described in the present scanning (SEM) and transmission electron microscopical (TEM) study. The suprabasal layers were removed mechanically after trypsinization or by extracellular calcium depletion. Trypsinization before removal of the suprabasal cells caused the basal cells to shrink. Characteristic surface plication and hemi-desmosomal attachment to the basement membrane were generally preserved. SEM revealed partly maintained intercellular bridging, whereas by TEM such contacts were absent because half desmosomes were internalized. Total calcium depletion induced more serious damage to the basal cell surface, which was smooth with apparent perforations. However, cell bridges, and occasional desmosomes were present. The cell interior demonstrated important cellular injury. If the calcium deprived explants were allowed to recover in calcium-containing medium, the cells acquired an activated "regenerative" morphology, without junctions, similar to that observed in wound healing. Epidermal non-keratinocytes were seen only after trypsinization. Control experiments revealed that they adapted poorly to organ culture conditions. By TEM, we observed several interesting aspects of the differences, between dark and clear basal keratinocytes. This was unexpected because fixation studies had shown, that with the present fixation method, typical dark and clear cells do not occur in untreated epidermis. We believe that membrane injury through mechanical stripping of partly adhering epidermal layers induced "clear cells", whereby the neighboring cells appeared darker. This provides additional evidence as to the origin of the two sub-populations, dark and clear basal cells. The clear cells may be injured cells, caused by cell damage, and not by processes of cellular differentiation. The results of the present investigation supports the view that basal keratinocytes have a polygonal shape with numerous free surface extensions and they are anchored to the basement membrane with "foot pads". Our study also shows that SEM of the epidermal basal layer might be feasible. Various artifacts, however, must be considered, depending on the denudation method used. We prefer trypsinization to calcium depletion because it is less time-consuming and results in a cell morphology which in TEM is comparable to that of basal cells in untreated whole epidermis. Extra-cellular calcium depletion, however, might be useful as a method to prepare single cell suspensions for flow cytometry. Restoration of a normal calcium concentration after stripping, provides an opportunity to mimic wound healing in situ, as an alternative t
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PMID:The morphology of the denuded epidermal basal cell layer of the hairless mouse after different preparation methods. A scanning and transmission electron microscopical study. 257 Apr 85

The Eimer's organ and adjacent structures and their changes after infraorbital axotomy was examined with LM, TEM and SEM in the Japanese shrew mole, Urotrichus talpoides. Approximately 3,000 of Eimer's organ covers the hairless snout tip of this animal. It protrudes to the corium from epidermis, and consists of column-shaped core and the cylindrical peripheral structures. About a dozen of naked fibers ascend vertically in the core; one or a few of them runs amidst the core and the others along its circumferential part. Each fiber has shelf-like endings one in each of 5 to 7 succeeding cells in the upper part of the core. At the uppermost part of the core structure is an opaque degenerating cell. Neurites were considered to grow up with the epidermal cells to which their endings are attached. This pattern of nerve ending was clearly observed for the first time in this study. Usually 3 Merkel cells lie at the base of an Eimer's organ contacting with a soup-plate-shape nerve terminal. In the dermis, an encapsulated corpuscle enveloping a nerve endings is found underneath each Eimer's organ. After axotomy, ipsilateral nerve fibers and their endings totally disappeared from Eimer's organ in a week. Perforation in the domes, flattening of the dome surface, and degeneration of the encapsulated corpuscles appeared on the transected side. In addition to this, several features of degeneration also appeared on the contralateral side. It might be considered as an effect of disuse from the disorders of the other side.
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PMID:Ultrastructure of the Eimer's organs of the Japanese shrew mole, Urotrichus talpoides (Insectivora, Mammalia) and their changes following infraorbital axotomy. 340 Aug 78

Hairless mouse epidermis was separated from the underlying dermis using a 2 h incubation in 20 mM ethylenediaminetetraacetic acid (EDTA). The basal epidermis, thus exposed, was then examined using scanning electron (SEM), transmission electron (TEM), and light microscopy (LM). Sheets were also stained for: (i) Langerhans cell adenosine triphosphatase (ATPase), beta-glucuronidase, and la antigens; and, (ii) melanocyte 3,4-dihydroxyphenylalanine (DOPA)-oxidase. A regular distribution of protruding dendritic cells was observed superficial to the basal epidermis. These external dendritic cells were identified as Langerhans cells on the basis of subcellular morphology and distribution in the TEM. ATPase staining was Langerhans cell specific. The Langerhans cell population in hairless mouse epidermis was large, and evenly distributed in the interfollicular epidermis and the outer root sheath of degenerate hair follicles. The melanocyte population, in comparison, was negligibly small (4-5 cells per mm2).
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PMID:The Langerhans cell in hairless mouse epidermis. 641 9

Occlusion of the skin with a water-vapor-impermeable membrane following disruption of the permeability barrier prevents the epidermal changes which lead to the restoration of barrier function, suggesting that water transit could be an important regulatory signal for barrier repair. However, occlusion with a water-vapor-impermeable membrane also prevents the movement of gases, which could also potentially influence permeability barrier homeostasis. Since O2 is known to have an effect on epidermal cell function, we have determined the effect of gases containing different levels of O2 on barrier repair 6 h following topical treatment of hairless mice with acetone. The disrupted barrier of air-exposed animals (O2 approximately 20%) recovered by 50.8 +/- 3.4% (mean +/- SEM) after 6 h. Under flowing air (O2 approximately 20%), O2/CO2 95/5% and argon (O2 = 0%) the barrier recovered by 43.9 +/- 28, 36.2 +/- 8.5 and 39.2 +/- 4.6%, respectively. These values were not statistically different from each other. The slightly lower levels of recovery at 6 h with the flowing gases in comparison to exposure to static air probably can be attributed to a slight cooling of the skin caused by the flowing gases. These results suggest that exogenous O2 is neither required for barrier repair nor a signal for barrier repair.
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PMID:Role of exogenous oxygen in cutaneous barrier repair. 794 73

We report quantitative data on epidermal melanogenesis by established and new furocoumarins. The ears and dorsal skin of pigmented hairless mice were treated for 12 d with compounds in ethanol, at equi-optical concentrations, and exposed to subphototoxic doses of ultraviolet A. Increased pigmentation was observed with 6,4,4'-trimethylangelicin > psoralen > 8-methoxypsoralen > 5-methoxypsoralen > 4,4',5'-trimethylazapsoralen = bergamot oil. Assessment of melanocyte numbers and morphology in epidermal sheet dihydroxyphenylalanine preparations showed that 6,4,4'-trimethylangelicin was the best compound with 536 ear melanocytes/mm2 +/- 15 SEM compared with 46 +/- 4 in controls. Psoralen induced 297/mm2 +/- 33, compared with its methoxy derivatives with ranges between 200 and 240/mm2.6,4,4'-trimethylangelicin had a striking effect on dorsal skin with 462 +/- 18 melanocytes/mm2 compared to less than 80/mm2 in all other ultraviolet A treatment groups. Khellin, 5-GOP and ultraviolet A only and all non-ultraviolet A controls had no effect. Melanogenesis was associated with increased dendricity, melanocyte size, especially with 5-methoxypsoralen, and giant melanocytes were noted with some treatments. The potency of 6,4,4'-trimethylangelicin, which does not form DNA interstrand crosslinks, may be related to its high DNA binding constant. Our data may be useful in the selection of compounds to treat vitiligo.
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PMID:Quantitative assessment of epidermal melanogenesis in C3H/Tif hr/hr mice treated with topical furocoumarins and UVA radiation. 802 88

We studied the interaction between the vasoconstriction evoked by postganglionic sympathetic neurones (sympathetic vasoconstriction) and the vasodilatation mediated by small-diameter afferent neurones (antidromic vasodilatation) in hairless skin of anaesthetized rats kept under controlled conditions. In all animals both the lumbar sympathetic trunk (LST) and the ipsilateral dorsal root (DR) L5 were surgically exposed, sectioned and electrically stimulated using different protocols. This experimental approach results in the exclusive and selective activation of sympathetic efferents and primary afferents respectively. Blood flow responses were measured using laser Doppler flowmetry. Sectioning the LST resulted in a pronounced increase in cutaneous blood flow by 112+/-15% (mean+/-SEM, n=25) indicating that ongoing sympathetic vasoconstrictor activity had been abolished. When a brief antidromic vasodilatation was produced by DR stimulation with 10-15 pulses at 1 Hz with C-fibre intensity during a sustained sympathetic vasoconstriction, peak blood flow reached preconstriction levels at LST stimulation frequencies of < or = 3 Hz. By contrast, antidromic vasodilatation was reduced at sympathetic stimulation frequencies of > or = 5 Hz and absent when stimulating the LST with 20 Hz. A similar response characteristic was obtained when LST and DR stimulation were started simultaneously. Continuous DR stimulation with 0.1 Hz evoked a substantial increase in cutaneous blood flow by 38+/-10% (mean+/-SEM, n=8) to a new baseline level. When sympathetic vasoconstriction was elicited on this background DR stimulation, the responses were smaller at all sympathetic frequencies. However, the maximum decrease in blood flow was significantly smaller than the controls at LST stimulation with < or = 3 Hz but not at higher frequencies. We conclude that sympathetic vasoconstriction and antidromic vasodilatation are competitive influences in the control of cutaneous blood flow. At low levels of cutaneous sympathetic vasoconstrictor activity, which probably prevail under resting conditions in the absence of cold stress, antidromic vasodilatation overrides sympathetic vasoconstriction. At high levels of cutaneous sympathetic activity, which may be reached in normal life under the conditions of severe cold, sympathetic vasoconstriction can suppress antidromic vasodilatation almost totally.
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PMID:Interaction of sympathetic vasoconstriction and antidromic vasodilatation in the control of skin blood flow. 910 8

We quantitatively investigated sympathetic vasoconstriction and antidromic vasodilation mediated by small-diameter primary afferents on the plantar hairless skin of the hindpaws in Wistar rats using laser Doppler (LD) flowmetry and an infrared thermometer. Sympathetic vasoconstriction was elicited by electrical stimulation of the centrally cut ipsilateral lumbar sympathetic trunk (LST) with 50-s trains at 0.1-20 Hz. Antidromic vasodilation was evoked by electrical stimulation of the dorsal root (DR) L5 with 20-s or 50-s trains at 1-4 Hz. Cutting the LST resulted in increases in skin temperature (SKT) by 6.1 +/- 1.0 degrees C (mean +/- SEM) and in LD flow by 128 +/- 20%. Stimulation of the LST resulted in a graded decrease in LD flow and SKT that was most pronounced between 0 and 0.1 Hz. However, DR stimulation evoked a large increase in LD flow but only little change in SKT in rats with sectioned LST. When the DR was stimulated either in animals with intact LST or during continuous stimulation of vasoconstrictor fibres in the sectioned LST, i.e. while baseline temperature was relatively low (26.3 +/- 1.1 degrees C), DR stimulation still resulted in large increases in LD flow, but only minor changes in SKT. These results suggest that blood flow through both deep and superficial layers of rat hairless skin is regulated by activity in sympathetic postganglionic vasoconstrictor fibres, whereas small-diameter primary afferent fibres appear to influence predominantly the blood flow through superficial layers of rat plantar skin.
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PMID:Functional evidence for the differential control of superficial and deep blood vessels by sympathetic vasoconstrictor and primary afferent vasodilator fibres in rat hairless skin. 954 92

Our aim was to analyse the effect of Gentacoll on the rate of epithelialisation and neovascularisation in wound healing. Standardised circular full thickness dermal wounds 2.25 mm in diameter were created on the dorsum of each ear on 24 hairless homozygous mice (n = 48). The cartilaginous layer was left intact. The wounds were treated in a randomised blinded fashion with bovine collagen implants with gentamicin (Gentacoll) (n = 17); bovine collagen implants without gentamicin (n = 15); and Silicone film (n = 16). Epithelialisation and neovascularisation were measured directly by intravital video-microscopy and computerised planimetry immediately after the wounds had been made and every third day until the wounds closed. Only five of the wounds treated with Gentacoll (n = 17) epithelialised completely; and their mean (SEM) epithelialisation time was 22.8 (1.6) days, significantly longer than controls without gentamicin (n = 15) for which the corresponding figures were 14.5 (0.6) days. In nine wounds treated with Gentacoll the ear cartilage in the wound bed perforated and two wounds developed severe inflammation, which was followed by self-mutilation. Neovascularisation was incomplete in all of the wounds in the Gentacoll group, whereas it was completed by 25.3 (0.7) days in the control group treated with implants without gentamicin. In the silicone treated group (n = 16), epithelialisation was completed by 12.7 (0.7) days and neovascularisation by 25.1 (0.5) days. None of wounds treated with collagen or silicone alone showed reactions similar to the Gentacoll-treated ears. Gentacoll hampers epithelialisation and neovascularisation, and might damage exposed cartilage.
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PMID:Gentacoll hampers epithelialisation and neovascularisation in excisional wounds in hairless mice. 964 60

The effect of topical cod liver oil ointment on the rate of wound epithelialisation and neovascularisation was studied using the hairless mouse ear wound model (experiment I). The effect of local application of vitamin A in increasing concentrations was tested in the same model (experiment II). Experiment I: Bilateral standardised full thickness dermal wounds were created on the ears of 42 mice divided into three groups: group I: 25% cod liver oil ointment (n = 10) applied topically to one ear and vehicle (vaseline) to the other; group II: 25% cod liver oil ointment (n = 10) and saline; and group III: vehicle (n = 22) and saline. Experiment II: Using the same model and procedures wounds were made on 12 mice randomised to vitamin A treatment in various doses (250-3000 IU/g) on one ear and vehicle (vaseline) on the other ear. Using in-vivo microscopy and digitised planimetry, wound epithelialisation and neovascularisation were measured at regular intervals until the processes were complete. Wounds treated with 25% cod liver oil ointment epithelialized significantly (p < 0.05) faster (mean (SEM) 8.9 (0.7) days) than control ears treated with vehicle alone (13.9 (1.9) days). Neovascularisation developed significantly faster (p < 0.01) in the ears treated with cod liver oil ointment (22.5 (1.3) days) compared with their vehicle control (29.1 (0.6) days). Neovascularisation was also significantly (p < 0.05) faster in the ears treated with cod liver oil ointment (23.1 (1.4) days) than in those treated with saline (26.8 (1.1) days). There was no significant difference in speed of epithelialisation between cod liver oil ointment and saline. The vitamin A dose study showed that epithelialisation and neovascularisation of the vitamin A treated wounds pass at the same rate as wounds treated with cod liver oil ointment. In conclusion, topical 25% cod liver oil ointment significantly accelerated both the epithelial and the vascular component of healing compared with saline. Vitamin A seems to have an important role in accelerating wound healing and could be the active component in cod liver oil.
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PMID:Topical application of cod liver oil ointment accelerates wound healing: an experimental study in wounds in the ears of hairless mice. 1075 71


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