The Stratum Corneum as an Organ of Protection: Old and New Concepts

Keratinocytes undergo maturation during their transit through the viable layers of skin, and then abruptly transform into flattened, anuclear corneocytes that constitute the cellular component of the skin barrier, the stratum corneum (SC). The SC is generally considered to be homogeneous in its structure and barrier properties, and is often shown schematically as a featureless brick wall, the “bricks” being the corneocytes, the “mortar” being intercellular lipid. Previously we showed the outer SC was not homogeneous in its composition, but contained steep gradients of the physiological inorganic elements Na, K and Cl, likely originating from sweat salts. Here we show the innermost corneocytes in human skin are also heterogeneous in composition, undergoing systematic changes in intracellular element concentration during transit into the interior of the SC.Human skin biopsies were taken from the lower leg of individuals with both “good” and “dry” skin and plunge-frozen in a stirred, cooled isopentane/propane mixture.

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Paracrystalline Aggregates of Psoriatic Keratin and Their Relation to Normal Keratin Structure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100120096 ◽

1985 ◽

Vol 43 ◽

pp. 680-681

Author(s):

S. Trachtenberg ◽

P.M. Steinert ◽

B.L. Trus ◽

A.C. Steven

Keyword(s):

Cell Death ◽

Stratum Corneum ◽

Intermediate Filament ◽

Skin Disease ◽

Amorphous Matrix ◽

Terminal Differentiation ◽

Proteolytic Degradation ◽

Horny Layer ◽

Chronic Skin ◽

Chronic Skin Disease

During terminal differentiation of vertebrate epidermis, certain specific keratin intermediate filament (KIF) proteins are produced. Keratinization of the epidermis involves cell death and disruption of the cytoplasm, leaving a network of KIF embedded in an amorphous matrix which forms the outer horny layer known as the stratum corneum. Eventually these cells are shed (desquamation). Normally, the processes of differentiation, keratinization, and desquamation are regulated in an orderly manner. In psoriasis, a chronic skin disease, a hyperkeratotic stratum corneum is produced, resulting in abnormal desquamation of unusually large scales. In this disease, the normal KIF proteins are diminished in amount or absent, and other proteins more typical of proliferative epidermal cells are present. There is also evidence of proteolytic degradation of the KIF.

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Novel Approaches to Low-Voltage Scanning Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100180586 ◽

1990 ◽

Vol 48 (1) ◽

pp. 366-367

Author(s):

Arthur V. Jones

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Low Voltage ◽

Electron Optics ◽

Current Interest ◽

New Concepts ◽

Opportune Time ◽

Novel Approaches ◽

Voltage Scanning ◽

Scanning Electron

In comparison with the developers of other forms of instrumentation, scanning electron microscope manufacturers are among the most conservative of people. New concepts usually must wait many years before being exploited commercially. The field emission gun, developed by Albert Crewe and his coworkers in 1968 is only now becoming widely available in commercial instruments, while the innovative lens designs of Mulvey are still waiting to be commercially exploited. The associated electronics is still in general based on operating procedures which have changed little since the original microscopes of Oatley and his co-workers.The current interest in low-voltage scanning electron microscopy will, if sub-nanometer resolution is to be obtained in a useable instrument, lead to fundamental changes in the design of the electron optics. Perhaps this is an opportune time to consider other fundamental changes in scanning electron microscopy instrumentation.

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