Diseases of the skin / by J. Ferguson Smith.

  • Smith, J. Ferguson.
Date:
[between 1900 and 1920]
Catalogue details

Licence: In copyright

Credit: Diseases of the skin / by J. Ferguson Smith. Source: Wellcome Collection.

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    STRUCTURE AND FUNCTIONS OF THE SKIN. Describe the Structure of the Skin. The skin consists of an epithelial portion, the epidermis, and a connective-tissue portion, the dermis or corium. Describe the Epidermis. The epidermis consists of five layers, which are to be re¬ garded rather as stages in the development of the epidermal cell than as separate structures. They are (from within out) the basal layer, the Malpighian or prickle-cell layer, the stratum granulosum, the stratum lucidum, and the stratum corneum or horny layer. Commencing at the level of the stratum granu¬ losum, the epidermal cell becomes converted into horn, the nucleus being lost at the level of the stratum lucidum. These flattened, horny cells are shed impalpably one by one. The basal and Malpighian layers are deeply indented, so as to inter- digitate with the papillae of the corium. The portions of epidermis between the papillae are known as interpapillary pro¬ cesses. The epidermis is devoid of blood-vessels. It is traversed by hair-follicles and the ducts of sweat-glands. Describe the Structure of the Corium. The corium consists of two parts : an, upper, the pars papil¬ laris, and a lower, the pars reticularis. The pars papillaris is composed of loose, white, fibrous tissue, with a fine network of elastic fibrils. It consists of finger-like processes, which fit into the indentations of the epidermis, and are known as papillae. The pars reticularis is continuous with the pars papillaris. Its fibres, both white and elastic, are coarser and more closely set. What is a Hair-follicle ? A hair-follicle is an invagination of the epidermis, which shows all the layers of the latter, with slight modifications. It runs down through the corium, often into the hypodermic
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