Cell junctions: tight, adherens, desmosomes, gap, hemidesmosomes !
- Topic
Cell junctions seal, glue and connect neighbouring cells; when the immune system attacks them, the skin blisters.
Updated 2026-11-01
See it in 3D: Skin · Esophagus · Jejunum
What it is
Epithelial cells attach to each other and to the basement membrane through specialised protein complexes. Tight junctions seal the space between cells, adherens junctions and desmosomes give mechanical strength, gap junctions let ions pass, and hemidesmosomes anchor the cell to the basal lamina. Several blistering diseases and tumours depend on them.
Structure
- Individual junctions are not visible on H&E; in stratified squamous epithelium the desmosomes show as «intercellular bridges» in the stratum spinosum.
- On TEM the apical junctional complex runs from top to bottom: tight junction, adherens junction, desmosome.
- In cardiac muscle the intercalated discs combine adherens junctions, desmosomes and gap junctions.
Cell junctions
| Junction | Main protein | Function | Disease |
|---|---|---|---|
| Tight junction (zonula occludens) | Claudins and occludin | Seals the intercellular space; separates apical from basolateral domains | Familial hypomagnesaemia (claudin-16); target of C. perfringens toxin |
| Adherens junction (zonula adherens) | E-cadherin (calcium-dependent), catenins, actin | Adhesion belt linked to microfilaments | Loss of E-cadherin in diffuse gastric and lobular breast carcinoma |
| Desmosome (macula adherens) | Desmogleins and desmocollins, desmoplakin, intermediate filaments | Mechanical strength in skin and myocardium | Pemphigus vulgaris (antibodies to desmoglein 3, sometimes 1) |
| Gap junction (nexus) | Connexins (connexon) | Passage of ions and small molecules; electrical coupling | Inherited deafness from connexin 26 |
| Hemidesmosome | Integrin alpha6-beta4, BP180 (collagen XVII), BP230 | Anchors the basal cell to the basal lamina | Bullous pemphigoid (antibodies to BP180 and BP230) |
Clinical notes
- Pemphigus vulgaris: flaccid intraepidermal blisters, often starting in the mouth; suprabasal acantholysis on biopsy and net-like IgG around keratinocytes on immunofluorescence.
- Bullous pemphigoid: tense subepidermal blisters in older people; linear deposits along the basement membrane; the mouth is usually spared.
- Nikolsky sign: the skin peels away when rubbed; typical of pemphigus vulgaris.
Test yourself
Think of the answer, then tap the question to see it.
Which protein do the antibodies of pemphigus vulgaris target?
Desmoglein 3 (sometimes 1), a desmosomal protein; the result is acantholysis and intraepidermal blisters.
Which junction seals the space between neighbouring epithelial cells?
The tight junction (zonula occludens), made of claudins and occludin.
Which proteins form gap junctions?
Connexins, which assemble into connexons that form channels between neighbouring cells.
Where does the blister of bullous pemphigoid form?
Below the epidermis, because the hemidesmosomes that anchor basal cells to the basement membrane fail.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Simple, stratified, pseudostratified and transitional epithelium
- Basement membrane
- Cytoskeleton: microfilaments, intermediate filaments, microtubules
- Where blisters form: pemphigus vs pemphigoid
- Cardiac muscle: intercalated discs
Related conditions
Educational content on normal microscopic structure and its clinical relevance; no substitute for studying slides or for a health professional's advice.
Sources: 4.2 Epithelial Tissue (OpenStax (Rice University), 2022); Pemphigus vulgaris (MedlinePlus (U.S. National Library of Medicine), 2024).
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Representative model, for educational purposes only.