Skin Biopsy Specimen

Point and click for more information on a feature.

Features which can be seen in this image include:

• Stratum corneum, or cornified layer, of the epidermis
  • This layer consists of dead keratinocytes.
• (The stratum granulosum is the thin, dark layer between stratum corneum and stratum spinosum, not separately labelled on this micrograph.)
• Stratum spinosum, or prickle-cell layer, of the epidermis.
  • Desmosomal junctions should be clearly visible at high power in your microscope. It is the spiny or prickly appearance of these junctions which give this epidermal layer its name.')
  • The epidermis appears unusually thick in this view.  This is an illusion, an artefact of the plane of section which has cut the epidermis obliquely.  Such plane-of-section effects can vary from place to place within a single section, because the tissue being sectioned may be curved or twisted.  As objective evidence for this oblique plane-of-section, note:
    •  The epidermis appears much thinner in adjacent areas (return to the lower-magnification view to see this, or click here).  Although the thickness of epidermis does vary regionally on the body, it usually does not change markedly over such small distance.
    • The presence of an "island" of connective tissue, apparently surrounded by epidermis, suggests that the epidermis has not been cut neatly perpendicular to its surface.  This is a dermal papilla.
• Stratum basale, or basal layer, of the epidermis
  • This layer includes mitotically active keratinocytes and melanocytes.
• Melanocytes in the basal layer of the epidermis.
  • Melanocytes are typically recognizable by the pale halo surrounding the nucleus.  This appearance results partly from pale (weakly staining) cytoplasm and partly from artifactual cell shrinkage.
  • (The cytoplasm of keratinocytes, which form the bulk of the epidermis, is much more basophilic.  Keratinocytes are also reinforced by intracellular fibers and are tightly attached to one another, so keratinocytes do not display this shrinkage characteristic.)
  • Although not obvious in this digitized micrograph, melanocytes also differ from keratinocytes in the appearance their nuclei.  Melanocyte nuclei are smaller, darker with grainier chromatin, and have less-conspicuous nucleoli.
• Connective tissue of dermis, with fibers and ground substance.
  • The papillary layer of the dermis lies just beneath the epidermis and contains finely-textured collagen fibers.
  • The reticular layer of the dermis lies deep to the papillary layer and contains coarsely-textured collagen fibers.
• Several small blood vessels.
• Many small features (such as individual fibroblasts and collagen fibers) are not individually labelled.

Comments and questions: dgking@siu.edu

SIUC / School of Medicine / Anatomy / David King

http://www.siumed.edu/~dking2/intro/skinbiop/du1SD3a1.htm
Last updated:  1 August 2002  / dgk