Human Anatomy
Integumentary System Histology
Integumentary system histology for MBBS: epidermal layers, dermal layers, skin cells, appendages and sensory corpuscles, mapped to NMC code AN72.1.
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Integumentary System Histology
Integumentary system histology for MBBS: epidermal layers, dermal layers, skin cells, appendages and sensory corpuscles, mapped to NMC code AN72.1.
This chapter describes the layered structure of the epidermis and dermis, the resident cell types and the skin appendages. It correlates the histology with the barrier, sensory and thermoregulatory functions of the skin.
High-yield: Integumentary System Histology
- The skin has two main layers, the epidermis of stratified squamous epithelium and the underlying dermis of connective tissue.
- The epidermis has, from deep to superficial, the stratum basale, spinosum, granulosum, lucidum and corneum.
- The stratum lucidum is present only in thick, hairless skin such as the palms and soles.
- Keratinocytes are the main epidermal cells and produce the protective protein keratin.
- Melanocytes in the stratum basale produce melanin, which shields against ultraviolet light.
- Langerhans cells are antigen-presenting immune cells scattered in the epidermis.
- Merkel cells in the basal layer are associated with fine touch sensation.
- The dermis has a superficial papillary layer and a deeper reticular layer of dense irregular connective tissue.
- Dermal papillae interlock with epidermal ridges and carry capillary loops and touch receptors.
- Meissner's corpuscles in the dermal papillae detect light touch and Pacinian corpuscles in the deep dermis detect pressure and vibration.
- The skin appendages are the hair follicles, sebaceous glands, sweat glands and nails.
- Sebaceous glands are holocrine and usually open into hair follicles to secrete oily sebum.
- Eccrine sweat glands are widespread and regulate temperature, while apocrine sweat glands open into hair follicles in the axilla and groin.
- The arrector pili muscle is smooth muscle that raises the hair and is attached to the follicle.
- The hypodermis or superficial fascia beneath the dermis is loose connective tissue rich in fat.
Layers and cells of the skin
- **Epidermal layers:** Basale, spinosum, granulosum, lucidum, corneum. Lucidum only in thick palmar and plantar skin.
- **Epidermal cells:** Keratinocytes make keratin; melanocytes make melanin; Langerhans cells present antigen; Merkel cells sense touch.
- **Dermal layers:** Papillary layer with capillary loops and touch receptors; reticular layer of dense irregular tissue.
- **Appendages:** Hair follicles, holocrine sebaceous glands, eccrine and apocrine sweat glands, nails, arrector pili muscle.
NMC competencies in this chapter
- **AN72.1:** Identification of skin and its appendages under the microscope with structure-function correlation
Frequently Asked Questions
What are the layers of the epidermis?
From deep to superficial they are the stratum basale, stratum spinosum, stratum granulosum, stratum lucidum and stratum corneum. The stratum lucidum is only present in thick, hairless skin.
Which cells are found in the epidermis?
Keratinocytes that make keratin, melanocytes that make protective melanin, Langerhans cells that present antigen, and Merkel cells associated with touch.
What is the difference between eccrine and apocrine sweat glands?
Eccrine glands are widespread and open directly onto the skin surface for thermoregulation. Apocrine glands are found mainly in the axilla and groin and open into hair follicles.
What are Meissner's and Pacinian corpuscles?
Meissner's corpuscles lie in the dermal papillae and detect light touch, while Pacinian corpuscles lie deeper in the dermis and detect pressure and vibration.
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