Stratified Columnar Epithelium
Stratified Columnar Epithelium
Section titled “Stratified Columnar Epithelium”At a glance
Section titled “At a glance”- Multilayered epithelium with columnar surface cells over cuboidal/basal cells; built for ducts and transition zones needing durability plus secretion.
- Found in large salivary/pancreatic ducts, conjunctival fornix, distal male urethra, and anal transitional mucosa.
- Expect intact basal layer, sparse goblet/mucous cells depending on site, and smooth basement membrane.
- Basal cells often p63+/CK5/6+; luminal columnar cells CK7/CK19+, mucins variable by site.
Jump to sections
Section titled “Jump to sections”- Generalities
- Large Excretory Ducts of Major Salivary Glands (parotid, submandibular, sublingual > final, bigger ducts)
- Major / Interlobar Ducts of the Pancreas
- Conjunctival Fornix
- Male Urethra (distal / penile / spongy segments, and parts of membranous)
- Anorectal / Anal Transitional Zone
Anorectal / Anal Transitional Zone
Section titled “Anorectal / Anal Transitional Zone”Architecture
Section titled “Architecture”Short segment of stratified columnar or mixed columnar–cuboidal epithelium between rectal simple columnar and anal stratified squamous.
Why: the body rarely goes from glandular to skinlike in one step so it uses a buffer epithelium.
Two to three layers, surface columnar, lower cuboidal.
Why: can adapt upward to intestinal type or downward to squamous if the environment changes.
Cytologic Features
Section titled “Cytologic Features”Columnar cells on the rectal side, progressively shorter toward the anal side.
Why: reflects the gradient in mechanical stress.
Mucin containing cells may be present near the rectal end.
Why: continuity with colorectal mucosa.
Polarity and Junctions
Section titled “Polarity and Junctions”Tight apical junctions.
Why: material in this area is dirty and can inflame the mucosa.
Desmosomes and strong lateral adhesion.
Why: anal canal is a high friction zone.
Basement Membrane
Section titled “Basement Membrane”Continuous and sometimes thicker.
Why: submucosa here is vascular and irregular so the BM evens it out for the epithelium.
Functional Correlation
Section titled “Functional Correlation”Role: epithelial shock absorber between fragile columnar rectal mucosa and tough anal squamous epithelium.
Why: stool passage, wiping and moisture vary a lot in this zone.
Injury and Repair
Section titled “Injury and Repair”Chronic irritation or infection can drive squamousization.
Why: body upgrades to the hardest available lining.
Biomarkers / IHC
Section titled “Biomarkers / IHC”Common epithelial markers positive: pan-CK, CK7 variable, CK19 variable, EMA.
Toward the rectal side: CK20 and intestinal mucins can appear.
Why: shows influence of colorectal mucosa.
Toward the anal side: high molecular weight keratins can increase.
Why: shows shift toward squamous phenotype.
Negative: vascular and hematolymphoid markers.
Why: confirms epithelial origin in polypoid or reactive lesions.
Conjunctival Fornix
Section titled “Conjunctival Fornix”Architecture
Section titled “Architecture”Stratified columnar, usually 2–3 layers, with goblet cells interspersed.
Why: the eye surface needs both protection from blinking and a mucin layer to stabilize the tear film.
Basal cells small on a basement membrane.
Why: supply for regeneration in chronic irritation or dryness.
Cytologic Features
Section titled “Cytologic Features”Surface columnar cells with clear or pale cytoplasm.
Why: adapted to a moist surface.
Goblet cells with mucin-filled cytoplasm.
Why: they secrete MUC5AC that anchors the aqueous part of the tear film.
Polarity and Junctions
Section titled “Polarity and Junctions”Tight junctions apically.
Why: prevents desiccation and entry of pathogens.
Desmosomes to resist blinking friction.
Why: eyelids rub this area repeatedly.
Basement Membrane
Section titled “Basement Membrane”Continuous although sometimes thin or folded with the fornix.
Why: conjunctiva is mobile; BM keeps the epithelial map stable.
Functional Correlation
Section titled “Functional Correlation”Role: make a smooth, moist, mucin-coated, flexible surface.
Why: protects cornea and facilitates eyelid movement.
Injury and Repair
Section titled “Injury and Repair”Chronic conjunctivitis or allergy increases goblet cells or thickens the epithelium.
Why: inflammation signals the tissue to produce more mucin and more protection.
Biomarkers / IHC
Section titled “Biomarkers / IHC”Epithelial cells positive: pan-CK, CK7, often CK19, EMA.
Why: typical non-keratinized mucosal epithelium.
Goblet cells positive: MUC5AC.
Why: confirms mucin secreting conjunctival phenotype.
Negative: keratinization markers that are strong in epidermis.
Why: helps separate from squamous metaplasia.
Generalities
Section titled “Generalities”1. Architecture
Section titled “1. Architecture”Multiple layers of epithelial cells (true stratified epithelium; at least two layers, often 2–3)
Why: extra layers give protection against friction, chemical irritation, or variable lumen size. Thicker wall = safer surface.
Surface (apical) cells are tall and columnar (only the top layer is columnar; deeper ones are not)
Why: the body wants the lumen to have the specialized surface of a columnar cell (secretion, barrier, mucous handling) but still wants the safety of stratification underneath.
Basal and parabasal cells are cuboidal to low columnar (shorter cells near the basement membrane)
Why: these cells are better for proliferation and for anchoring to the basement membrane. They act as the “reserve” and the “scaffolding.”
All layers rest on a single basement membrane (even though many layers, still one base)
Why: epithelium always needs one organized support to attach to, to get nutrients from, and to regenerate along.
2. Cytologic Features
Section titled “2. Cytologic Features”Surface cells: tall, columnar, with eosinophilic cytoplasm (you can actually see the cytoplasm, unlike very thin epithelia)
Why: columnar cells can house more organelles, so they can secrete or maintain a better barrier.
Nuclei of surface cells: oval, vertical, at the same height (nuclei line up near the basal half of the columnar cells)
Why: aligned nuclei make the surface smoother and more regular, which helps when fluid passes over it.
Deeper cells: smaller, rounder nuclei, less cytoplasm (look more like cuboidal)
Why: these are mainly structural and progenitor-like. They do not need to do the lumen job.
Minimal pleomorphism in normal tissue
Why: uniformity tells you the lining is healthy and not dysplastic.
3. Polarity and Attachment
Section titled “3. Polarity and Attachment”Apical pole of surface cells faces the lumen (this is the business end)
Why: secretion, barrier control, and interaction with the lumen must all happen at the top.
Basal cells firmly attached to the basement membrane with hemidesmosomes
Why: stratified epithelia experience more stress. Strong basal attachment keeps the whole stack from sliding.
Lateral surfaces joined by junctional complexes, strongest in the upper layers
Why: the layer that touches the lumen is the one most likely to be rubbed or stretched, so it needs the tightest sealing.
4. Junctional Complexes
Section titled “4. Junctional Complexes”Tight junctions near the apical part of surface cells
Why: keeps lumen contents from leaking down between layers.
Adherens junctions and desmosomes between surface cells and also between suprabasal cells
Why: stratified columnar is often in sites that change diameter (large ducts, urethra). These junctions let the epithelium stay in one piece when the lumen distends.
Gap junctions may be present
Why: allows coordinated responses such as repair or secretion.
Basal hemidesmosomes to basement membrane
Why: anchor the epithelium against shear.
5. Basement Membrane
Section titled “5. Basement Membrane”Single, continuous basement membrane
Why: even if the top looks complicated, the stem/progenitor compartment needs one map to regrow along.
Composed of type IV collagen, laminin, proteoglycans
Why: standard epithelial attachment mix that allows both strength and migration during repair.
6. Cytoskeleton
Section titled “6. Cytoskeleton”Columnar surface cells rich in actin at the apical cortex
Why: helps maintain tall shape and supports any apical specializations (small folds, occasional microvilli).
Cytokeratin profile of stratified/ductal epithelia (often CK4, CK8, CK13, CK18, CK19 depending on site)
Why: tells you it is epithelial and often of mucosal/ductal origin.
Intermediate filaments connect to desmosomes
Why: spreads mechanical stress across cells so the top layer does not peel off.
7. Immunohistochemistry (site dependent)
Section titled “7. Immunohistochemistry (site dependent)”Pan-cytokeratin (AE1/AE3), broad-spectrum CKs: positive
Why: confirms epithelial nature.
High-molecular-weight keratins may be positive in the basal/suprabasal layers in some sites
Why: lower layers often express a more “protective” keratin pattern.
EMA often positive in surface cells
Why: consistent with luminal/mucosal differentiation.
Site-specific markers (e.g. in conjunctiva, salivary excretory ducts, male urethra)
Why: the same architecture can line different organs, and we identify origin with organ-specific markers if needed.
8. Vascularity and Nutrition
Section titled “8. Vascularity and Nutrition”Epithelium itself has no vessels
Why: vessels in the epithelial sheet would break with friction.
Nutrients diffuse from underlying vascular connective tissue
Why: thickness is still small enough to allow diffusion from below.
9. Functional Correlation
Section titled “9. Functional Correlation”Primary role: protection of a lumen that still needs a columnar surface
Why: some tubes cannot afford to lose the columnar advantages (secretion, better barrier, smoother surface) but they also face mechanical or chemical stress, so stratification is added.
Secondary role: limited secretion or mucous handling depending on site
Why: columnar cells can produce or modify secretions for ducts or mucosal surfaces.
Better resistance than simple columnar, but less than stratified squamous
Why: stratified squamous is the champion for abrasion, but it loses the tall-cell functions. Stratified columnar is the compromise form.
10. Regeneration and Injury
Section titled “10. Regeneration and Injury”Basal/suprabasal cells can proliferate and move upward
Why: surface columnar cells are more specialized; deeper cells act as the renewal compartment.
Repair is orderly if the basement membrane is intact
Why: as with other epithelia, the basement membrane is the guide rail for migration.
Chronic irritation can cause metaplasia to another stratified type
Why: the body may trade function for protection if the environment worsens.
11. Typical Anatomic Correlates
Section titled “11. Typical Anatomic Correlates”Large excretory ducts of salivary glands, pancreas, and other glands
Why: these ducts carry secretions and can be distended or irritated, so they need both protection and a columnar lumen.
Conjunctival fornix
Why: exposed to air, blinking, and secretions, so a tougher columnar lining helps.
Male urethra (distal parts)
Why: variable flow and potential irritation require extra layers but the lumen still benefits from columnar cells.
Anorectal junctional areas
Why: transition zones often use stratified columnar as an intermediate, protective lining.
Large Excretory Ducts of Major Salivary Glands (parotid, submandibular, sublingual > final, bigger ducts)
Section titled “Large Excretory Ducts of Major Salivary Glands (parotid, submandibular, sublingual > final, bigger ducts)”Architecture
Section titled “Architecture”Stratified epithelium with surface columnar cells (2–3 layers).
Why: final ducts are close to oral cavity so flow, pressure and oral irritants are higher. Extra layers protect the lumen.
Basal layer cuboidal on a single basement membrane.
Why: gives a stable frame so the lumen can change size without tearing.
Lumen round to slightly oval.
Why: smooth lumen allows saliva to pass without turbulence.
Cytologic Features
Section titled “Cytologic Features”Surface cells tall columnar with eosinophilic cytoplasm.
Why: columnar cells can still do a bit of modification and protection.
Nuclei elongated and aligned.
Why: aligned nuclei create a smoother inner wall for flow.
Deeper cells smaller, more cuboidal.
Why: these are the structural and regenerative cells.
Polarity and Junctions
Section titled “Polarity and Junctions”Apical surface faces the lumen with tight junctions.
Why: prevents saliva from leaking between cells.
Adherens junctions and desmosomes between suprabasal cells.
Why: duct gets squeezed during chewing so lateral adhesion must be strong.
Basement Membrane
Section titled “Basement Membrane”Continuous, relatively conspicuous basement membrane.
Why: salivary stroma is lobulated and mobile so the epithelium needs a firm floor.
Functional Correlation
Section titled “Functional Correlation”Role: protect the terminal duct from mechanical and chemical stress while keeping a clean lumen.
Why: secretion is basically finished but protection is still needed.
Injury and Repair
Section titled “Injury and Repair”Chronic sialadenitis may make it thicker or more squamoid.
Why: chronic inflammation pushes toward tougher epithelia.
Biomarkers / IHC
Section titled “Biomarkers / IHC”Positive: pan-cytokeratin (AE1/AE3), CK7, CK19, EMA.
Why: confirms ductal epithelial nature.
Usually negative: S100, SOX10 in the stratified part (those are more for acini and myoepithelium).
Negative: CD45 and endothelial markers.
Why: rules out inflammatory or vascular sheets.
Major / Interlobar Ducts of the Pancreas
Section titled “Major / Interlobar Ducts of the Pancreas”Architecture
Section titled “Architecture”Stratified columnar or stratified cuboidal–columnar, 2–3 layers.
Why: pancreatic juice is enzyme rich and can be irritating so the lining is reinforced.
Basal cells cuboidal on a single basement membrane.
Why: provides a regenerating base.
Cytologic Features
Section titled “Cytologic Features”Surface cells columnar with fine apical specializations.
Why: can slightly modify or protect the secretion near outflow.
Deeper cells smaller and more basophilic.
Why: structural and progenitor role.
Polarity and Junctions
Section titled “Polarity and Junctions”Tight junctions apically.
Why: prevents leakage of enzymes into duct wall which would be damaging.
Desmosomes between layers.
Why: pancreas moves with breathing and peristalsis around it so ducts must not split.
Basement Membrane
Section titled “Basement Membrane”Continuous basement membrane with periductal fibrous support.
Why: needed for repair in pancreatitis or obstruction.
Functional Correlation
Section titled “Functional Correlation”Role: barrier against activated or concentrated pancreatic secretions.
Why: lumen content is potentially autodigestive.
Injury and Repair
Section titled “Injury and Repair”Obstruction, chronic pancreatitis, or irritation can lead to squamoid or squamous metaplasia.
Why: body upgrades to the toughest lining it can afford.
Biomarkers / IHC
Section titled “Biomarkers / IHC”Positive: pan-CK (AE1/AE3), CK7, CK19, EMA.
Why: typical pancreatobiliary ductal profile.
Sometimes positive or focal: MUC1, MUC5AC in reactive or metaplastic settings.
Why: reflects mucosal protection.
Negative: endothelial (CD31, ERG), lymphoid (CD45).
Why: supports epithelial nature.
Male Urethra (distal / penile / spongy segments, and parts of membranous)
Section titled “Male Urethra (distal / penile / spongy segments, and parts of membranous)”Architecture
Section titled “Architecture”Stratified or stratified columnar epithelium with surface columnar cells and deeper cuboidal cells.
Why: urethra faces variable flow, occasional infection and chemical irritation from urine and semen so it needs extra layers.
Single basement membrane.
Why: standard epithelial support for regeneration.
Cytologic Features
Section titled “Cytologic Features”Surface cells columnar and sometimes mucin rich.
Why: lubrication and protection from urine.
Deeper cells small, basophilic.
Why: provide replacement cells.
Polarity and Junctions
Section titled “Polarity and Junctions”Tight junctions apically.
Why: urine is irritating and must not seep into the lamina propria.
Desmosomes present.
Why: urethra stretches during voiding.
Basement Membrane
Section titled “Basement Membrane”Continuous over vascular connective tissue.
Why: urethra is highly vascular and elastic so epithelium needs a firm floor.
Functional Correlation
Section titled “Functional Correlation”Role: keep a smooth lubricated lumen that still resists intermittent mechanical and chemical stress.
Why: the same tube is used for urine and for semen.
Injury and Repair
Section titled “Injury and Repair”Chronic urethritis, trauma or catheterization can lead to squamous metaplasia.
Why: if the environment is too harsh the body switches to a tougher squamous lining.
Biomarkers / IHC
Section titled “Biomarkers / IHC”Positive: pan-CK, CK7 common, CK19 variable, EMA.
Why: confirms epithelial and ductal/mucosal nature.
Sometimes positive or focal: GATA3 because of proximity to urothelium.
Why: transitional regions can show overlapping profiles.
Usually negative in distal segments: uroplakin.
Why: helps separate true urothelial lining from distal urethral stratified columnar.