Skin, epidermis and dermis

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Keratinized stratified squamous epithelium and dense fibrous connective tissue together comprise the skin.  

The epithelial tissue layer of skin, called the epidermis, is composed of cells attached to one another by numerous adhering junctions (maculae adherens, or desmosomes).

These epidermal cells are called keratinocytes because they accumulate keratin as they mature and migrate toward the surface.  They eventually becoming the tough, dead outer layer (stratum corneum) of the skin.

At high magnification, the cell junctions are visible as fine "prickles" extending across the gap (intercellular space) between adjacent keratinocytes.  The junctions are reinforced by tonofilaments which are rooted in the cells' cytoplasm.  

The connective tissue layer of skin, called the dermis, consists primarily of extracellular collagen fibers and ground substance.

In this H&E stained specimen, collagen appears pink (indicated by arrows in this thumbnail image).  Ground substance is unstained (i.e., the pale background color).  

Scattered within the extracellular matrix are individual cells.  The very dark purple (nearly black) spots are cell nuclei.  In the large image above, most of the dermal nuclei belong to fibroblasts.  Some may also belong to macrophages, mast cells, or capillary endothelial cells.  

 

Passing through the connective tissue of the dermis are blood vessels.  Capillaries and small vessels occur near the surface (as shown here).  The group of odd-shaped nuclei in the venule in the lower right corner belong to neutrophils.  Larger vessels may be found at deeper levels in the dermis and subcutaneous connective tissues.

   

Click here to view an interactive image with additional details labelled.

Comments and questions: dgking@siu.edu

SIUC / School of Medicine / Anatomy / David King

https://histology.siu.edu/intro/IN0008b1.htm
Last updated:  12 June 2022 / dgk