Page 476 - Atlas of Histology with Functional Correlations

arm.

Supplemental micrographic images are available at

www.thePoint.com/Eroschenko13e under Skin System.

FIGURE 12.2 | Thin Skin: Epidermis and

Contents of Dermis

This illustration depicts a section of thin skin from body surface, where wear and
tear is minimal. To differentiate between the cellular and connective tissue
components of the skin, the collagen fibers stain blue, and the cellular

components stain red.

The skin consists of two layers: the epidermis (10) and dermis (14). The
epidermis (10) is the superficial cellular layer with different cell types. The
dermis (14), located directly inferior to the epidermis (10), contains connective

tissue and cellular components of epidermal origin.

In thin skin, the epidermis (10) exhibits a stratified squamous epithelium and
a thin layer of keratinized cells called the stratum corneum (1), from which the
most superficial cells constantly shed or desquamate. Also, the stratum corneum
(1) of thin skin is much thinner in contrast to that of thick skin, in which the

stratum corneum (1) is much thicker. In this illustration, a few rows of polygonal
cells are visible in the epidermis (10). These cells form the stratum spinosum
(2).

The narrow zone of irregular, lighter-staining connective tissue directly

below the epidermis (10) is the papillary layer (11) of the dermis (14) that
indents the base of the epidermis to form the dermal papillae (3). The deeper
reticular layer (12) comprises the bulk of the dermis (14) and consists of dense
irregular connective tissue. A portion of the hypodermis (13), the underlying
subcutaneous adipose tissue (9), is also illustrated.

Skin appendages, such as the sweat gland (7) and hair follicles (8), develop
from the epidermis (10) and are located in the dermis (14). The sweat gland (7)
is illustrated in greater detail in Figure 12.4. The expanded terminal portion of
the hair follicle (8) observed in the longitudinal section is the hair bulb (8a)

with the base indented by the connective tissue to form a dermal papilla (8b).
Each dermal papilla (8b) contains a capillary network that is vital for sustaining
the hair follicle (8). Attached to hair follicles (8) are thin strips of smooth muscle

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