Skin: epidermis layers, dermis, hypodermis !

Organ

Skin has an outer epidermis of stacked cells, a strong dermis of collagen with vessels and nerves, and a fatty hypodermis underneath.

Updated 2026-11-01

See it in 3D: Skin

What it is

The epidermis is a keratinised stratified squamous epithelium with no blood vessels; its cells are born in the basal layer and move up, fill with keratin and die as they reach the surface. The dermis below is connective tissue: a loose papillary layer that interlocks with the epidermis and a dense reticular layer that gives strength. The hypodermis (subcutaneous tissue) is fat and loose connective tissue that cushions and insulates.

Structure

Dermal papillae and epidermal rete ridges interlock and resist shearing.
Papillary dermis holds capillary loops and Meissner corpuscles; reticular dermis holds hair follicles, glands and larger vessels.
Hypodermis contains fat lobules, larger vessels and Pacinian corpuscles.

Function

Barrier against water loss, microbes and UV light.
Temperature control by sweat and dermal blood flow.
Sensation, vitamin D synthesis and immune surveillance.

Epidermal layers, from deep to surface

Layer	What you see	What happens there
Stratum basale	One row of cuboidal to columnar cells on the basement membrane, with melanocytes and Merkel cells	Stem cells divide; hemidesmosomes anchor the epidermis to the dermis
Stratum spinosum	Several rows of polygonal cells that look spiny because of desmosomes	Keratin filaments build up; Langerhans cells patrol here
Stratum granulosum	A few rows of flattened cells with dark basophilic keratohyalin granules	Cells release lipid from lamellar bodies to form the water barrier and begin to die
Stratum lucidum	A thin clear band, only in thick skin	Dead, flattened cells packed with keratin precursors
Stratum corneum	Many layers of flat, anucleate pink scales	Dead keratin-filled cells form the barrier and are shed

Clinical notes

Psoriasis: thick epidermis with nuclei kept in the corneum (parakeratosis) and a thin or absent granular layer.
Superficial burns affect only the epidermis; partial-thickness burns reach the dermis and blister; full-thickness burns destroy both.
Melanoma thickness (Breslow) is measured in millimetres from the granular layer down to the deepest tumour cell.

Test yourself

Think of the answer, then tap the question to see it.

What are the epidermal layers, from deep to superficial, in thick skin?

Stratum basale, spinosum, granulosum, lucidum and corneum; thin skin lacks the lucidum.

Why do cells of the stratum spinosum look spiny on light microscopy?

Shrinkage during processing pulls cells apart except where desmosomes hold them, leaving spine-like bridges.

What is the main difference between the papillary and reticular dermis?

The papillary dermis is thin loose connective tissue with capillaries; the reticular dermis is thick dense irregular tissue that gives strength.

Which burn depth produces blisters?

A partial-thickness (second-degree) burn, which damages the epidermis and part of the dermis.

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See it in 3D

The structures of Durgical's 3D anatomy where it is found.

Skin

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Educational content on normal microscopic structure and its clinical relevance; no substitute for studying slides or for a health professional's advice.

Sources: 5.1 Layers of the Skin - Anatomy and Physiology 2e | OpenStax (OpenStax, Rice University, 2022); Anatomy of the Skin (National Cancer Institute, SEER Training Modules, 2024); 5.4 Diseases, Disorders, and Injuries of the Integumentary System - Anatomy and Physiology 2e | OpenStax (OpenStax, Rice University, 2022).

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Representative model, for educational purposes only.