Gartner_BRS Cell Biology & Histology, 9e

Chapter 12 Skin

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Meissner corpuscle

Stratum corneum Epidermis

Hair shaft

Sebaceous (oil) gland

Stratum spinosum

Arrector pili muscle

Reticular layer Papillary layer Dermis Stratum basale

Eccrine sweat gland

Apocrine sweat gland

Eccrine sweat gland

Hair follicle

Apocrine sweat gland

Hair root

Root hair plexus

Pacinian corpuscle Artery Vein

Hypodermis (superficial fascia)

Adipose tissue of hypodermis

ductal lumen spirals through the epidermis, is lined by the keratinocytes, and directly opens to the skin surface to form a sweat pore (see Fig. 12.2). b. The ductal cells in the dermis can modify the content of the sweat by reabsorbing some elec trolytes and excrete other substances (such as urea, lactic acid, ions, and certain drugs). PEARLS Hyperhidrosis is an excessive production of sweat by eccrine sweat glands, most commonly of the palms, soles, and axilla, beyond the thermoregulatory requirements. Hyperhidrosis may result from autonomic dysregulation or secondary to other conditions. The FDA approved an anticholinergic agent, glycopyr ronium tosylate, impregnated in a topical cloth in 2018 for primary axillary hyperhidrosis. Anticholinergic medications, sedatives, and calcium blockers can also be used for systemic treatment of hyperhidrosis. However, adverse side effects should be considered, such as xerostomia, dry eyes, and constipation. Botox injections are also anticholinergic and more effective at treating localized areas by directly intro ducing the neurotoxin into the skin on the palms, soles, or axillae. The toxin blocks sympathetic nerve impulses to the cells of the eccrine sweat glands and decreases their ability to secrete. A single injection of Botox may provide months of relief, and the injections can be repeated when excessive sweating resumes. Clinical Skin and its appendages, hair , sweat glands (both eccrine and apocrine ), sebaceous glands , and nails , are known as the integument . Skin may be thick or thin , depending on the thickness of its epidermis. Thick skin epidermis is composed of five distinct layers of keratinocytes (strata basale, spinosum, granulosum, lucidum, and corneum) interspersed with three additional cell types, melanocytes , Merkel cells , and Langerhans cells . Thin skin epidermis lacks strata granulosum and lucidum, although individual cells that constitute the absent layers are present. FIGURE 12.5. Diagram illustrating skin and its derivatives. (Reprinted with permission from Gartner LP, Lee LMJ. Gartner and Hiatt’s Atlas and Text of Histology . 8th ed. Wolters Kluwer; 2023:300.)

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