A practical treatise on diseases of the skin / by John V. Shoemaker.

  • Shoemaker, John V. (John Veitch), 1852-1910.
Date:
1888
Catalogue details

Licence: Public Domain Mark

Credit: A practical treatise on diseases of the skin / by John V. Shoemaker. Source: Wellcome Collection.

Provider: This material has been provided by University of Bristol Library. The original may be consulted at University of Bristol Library.

    18/680 (page 4)
    horny layer ; and the latter two likewise, and styled the mucous layer. This'classification is, however, erroneous, and should be discarded. There are four layers, whether viewed from a pathological or a histo- logical point of view. The epidermis varies in thickness in accordance with the develop- ment of its various layers. It is thinnest about the lips and on the face, and thickest upon the palms and soles. The coloring-matter of the epidermis is almost exclusively found in the stratum mucosum. Stratum Corneum (Corneous Later).—This is the external or superficial layer of the epidermis. It is composed of several strata of flattened, transparent cells of various shapes and sizes. The cells of the deeper are polygonal or spindle-shaped in form, and are larger and more distinct than those above them. Some present traces of a nucleus, and can be stained faintly with carmine. The superficial strata consist of flat, iDolymorphous scales, which become more and more shrivelled in appearance, and curved upon themselves as the sur- face is approached. They do not contain any nuclei. The stratum corneum varies in different portions of the body. It is thinnest on the lips and face, and thickest on the palms and soles. Its thickness does not depend on the development of the other layijrs of the epidermis. Stratum Lucidum.—The stratum lucidum, called also the stra^ tum of Oehl, after its first discoverer, is the narrow, transparent layer of compressed cells found immediately beneath the stratum corneum. According to Unna* it contains from four to six rows of cells that in fresh, unstained sections, attract attention by reason of their ex- treme transparency. They are derived from the cells of the grauuhir layer by the loss of that material, and the increase in transpai'ency of the rest of the cell-substance. Each cell contains a staff-shaped or flattened nucleus. Unna believes that this layer is merely a portion of the stratum corneum, and suggests that the title of stratum lucidum be abandoned, as incorrect and misleading. Stratum Granulosum.—The granular layer, or layer of Lan- gerhaus, consists of two or three rows of flattened, nucleated cells, which are situated immediately beneath the stratum lucidum. They were at one time supposed to be true connective-tissue corpuscles, be- cause of their spindle-shaped appearance when a vertical section of this layer is made. Their long diameter is parallel to the surface of the epidermis. They are characterized by the presence around their nuclei of a number of minute granules of a substance known as elcidin, which, according to Ranvier, is a material intermediate in nature be- tween protoplasm and keratin. It is most abundant near the nuclei of the cells, and diminishes or disappears as the periphery is ap^ preached. Unna regards the presence and formation of the granules * The Anatomy and Development of the Skin, in Ziemssen's Handbook of Dis- eases of the Skin.