ISSN:
0362-2525
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
A β-keratin pattern, consisting of 30 Å filaments embedded in an amorphous matrix, is formed by fusion of membrane-bound packets with the 70 Å filaments of immature cells. This pattern occurs in the Oberhäutchen and the β-layer. When completely mature, these two components show no cell boundaries. It is suggested that this feature is associated with the process that leads to the separation of outer and inner epidermal generation. Filaments of 100-150 Å embedded in an amorphous matrix form the α-keratin pattern, which occurs in the α-layer only. The lacunar tissue is regarded as consisting of cells resembling immature α-cells, whereas mesos and clear layer show a keratin-like material consisting of 100-150 Å filaments without matrix. This is regarded as a modification of α-keratin. The cells of all components synthesizing α-keratin (α, mesos and clear layer) have the following features in common: (1) the plasma membrane is modified in that its inner leaflet is obscured by the deposition of a marginal layer, and (2) the cells have 0.06-0.1 μm mucous granules containing mucopolysaccharides, which release their content into the intercellular space.Protective and barrier functions of the epidermis are provided by the following features: (1) Oberhäutchen and β-layer merge during final maturation to a homogenous stratum of β-keratin without intercellular spaces. Their function seems to be mechanical protection. (2) The marginal layer of α-keratin containing cells, which decreases in thickness from without inwards, is highly resistant to physical and chemical influences. (3) Mesos granules contain phos-pholipid-lamellae, which are partly discharged into the intercellular space and partly remain within the mesos cells. These lipid lamellae are believed to contribute to the establishment of the permeability barrier. (4) The content of mucous granules may play a role in immunological processes. (5) Tight junctions seal off the intercellular space between the uppermost living cells of the epidermis and contribute to the permeability barrier.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jmor.1051620107
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