WORKSHOP IN HISTOLOGY, CYTOLOGY AND EMBRYOLOGY - 2016

Chapter 5. SPECIAL HISTOLOGY

Skin and its appendages

Slide 117. Non-hairy skin.

Staining: hematoxylin and eosin.

Magnification: x80.

Under low magnification, observe the epidermis and the dermis (corium), which projects deeply into the epidermis via prominent dermal papillae, thus forming the papillary layer. Deeper down lie the reticular layer of the dermis and the subcutaneous layer (hypodermis).

The epidermis features a basal layer (1) composed of columnar Cells. The Cell boundaries are difficult to distinguish; their nuclei are large, spherical, and purple. Overlying the basal layer is the stratum spinosum, or spinous layer (2). Its cell nuclei are large, round, and lighter in color than those of the basal layer, with the Cytoplasm spanning a larger area. In the Cells of the superficial rows of the spinous layer, small dark granules appear, marking the onset of keratinization. In the cells of the subsequent granular layer (3), keratohyalin granules fill the entire cytoplasm. Next is the stratum lucidum (4). Its cell boundaries are indistinct, nuclei are absent, and the cytoplasm is filled with elaidin, which strongly refracts light. The outermost layers are the stratum corneum and the disjuncted layer, consisting of anucleated postcellular structures—squames (5).

The papillary layer of the dermis (6) is formed by loose Connective Tissue, which is rich in Blood Vessels and nerve endings.

The reticular layer of the dermis (7) is represented by dense irregular connective tissue containing numerous thick bundles of Collagen fibers oriented in various directions. Interspersed among them are the nuclei of connective tissue cells, predominantly fibroblasts. The secretory portions of Sweat Glands are also located here (8).

The deepest layer is the subcutaneous layer—the hypodermis (9).

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Slide 117. Non-hairy Skin.