A 78-year-old man in a geriatric ward has itchy, tense blisters on the flexures of his arms and thighs, with no mouth involvement. Biopsy shows a subepidermal blister, and direct immunofluorescence shows linear IgG and C3 along the basement membrane zone. Which structure is targeted by his antibodies?

Anchoring fibrils of type VII collagen

A 58-year-old man who has smoked bidis for 40 years undergoes bronchoscopy for a chronic cough. Biopsy of the main bronchus shows stratified squamous epithelium. Which epithelium normally lines this site?

Pseudostratified ciliated columnar

Non-keratinised stratified squamous

A 9-year-old boy has had a wet cough and nasal discharge since infancy, with repeated ear infections. HRCT shows bronchiectasis, and the chest X-ray shows the cardiac apex on the right. Nasal nitric oxide is very low. Which structure is most likely abnormal in his cells?

Dynein arms of the ciliary axoneme

Claudins of the tight junctions

Type IV collagen of the basement membrane

Histology and cell biology

8 NEET-PG practice questions on Histology and cell biology, part of Anatomy. The first 8 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Medium
A 78-year-old man in a geriatric ward has itchy, tense blisters on the flexures of his arms and thighs, with no mouth involvement. Biopsy shows a subepidermal blister, and direct immunofluorescence shows linear IgG and C3 along the basement membrane zone. Which structure is targeted by his antibodies?
1. AAnchoring fibrils of type VII collagen
2. BAdherens junctions
3. CDesmosomes
4. DHemidesmosomes
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Answer: D · Hemidesmosomes
Bullous pemphigoid is caused by autoantibodies against BP180 (type XVII collagen) and BP230, proteins of the hemidesmosome that anchor basal keratinocytes to the basement membrane. Complement activation and inflammatory cells separate the epidermis from the dermis, giving a tense subepidermal blister that does not rupture easily. It mainly affects the elderly and spares the mucosa in most patients. It responds to potent topical or oral steroids.
- A: Antibodies to type VII collagen cause epidermolysis bullosa acquisita, with blistering at trauma sites.
- B: Adherens junctions link actin of neighbouring cells and are not targets in pemphigoid.
- C: Desmosome antibodies cause pemphigus, with intraepidermal flaccid blisters.
Question 2 · Hard
A second-year resident teaching epithelial junctions to medical students writes four statements on the board: 1. Tight junctions, built of claudins and occludin, seal the paracellular space. 2. Adherens junctions anchor keratin intermediate filaments. 3. Hemidesmosomes attach basal cells to the basal lamina through integrins. 4. Gap junctions are built of connexins. Which statements are correct?
1. A1 and 4 only
2. B1, 2 and 4 only
3. C1 and 3 only
4. D1, 3 and 4 only
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Answer: D · 1, 3 and 4 only
Statements 1, 3 and 4 are correct. Tight junctions (zonula occludens) use claudins and occludin to block passage between cells; hemidesmosomes link keratin filaments through integrin alpha-6 beta-4 and type XVII collagen to the basal lamina; and gap junctions are channels made of connexins. Statement 2 is false: adherens junctions (zonula adherens) link cadherins to actin filaments, while desmosomes are the junctions anchored to keratin. Loss of E-cadherin from adherens junctions is important in tumour invasion, for example in diffuse gastric and lobular breast cancer.
- A: Leaves out statement 3: hemidesmosomes do anchor cells through integrins.
- B: Includes statement 2, which describes desmosomes, and leaves out statement 3.
- C: Leaves out statement 4: gap junctions are indeed built of connexins.
Question 3 · Easy
A 45-year-old woman has painful oral erosions for two months, followed by flaccid blisters on her trunk that rupture easily. Gentle pressure on normal-looking skin makes the epidermis slide off. Antibodies against which cell junction cause this disease?
1. ATight junctions
2. BDesmosomes
3. CHemidesmosomes
4. DGap junctions
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Answer: B · Desmosomes
This is pemphigus vulgaris. IgG autoantibodies against desmoglein 3 (and often desmoglein 1), cadherins of the desmosome, separate keratinocytes from each other (acantholysis) just above the basal layer. The blister is therefore intraepidermal and flaccid, and the Nikolsky sign is positive. Direct immunofluorescence shows intercellular IgG in a net-like pattern, and treatment is with corticosteroids and rituximab.
- A: Tight junctions seal the paracellular space and are not the target in pemphigus.
- C: Antibodies to hemidesmosomes cause bullous pemphigoid, with tense subepidermal blisters.
- D: Gap junctions allow cell-to-cell communication; their defects cause some deafness and skin disorders, not autoimmune blisters.
Question 4 · Easy
A 58-year-old man who has smoked bidis for 40 years undergoes bronchoscopy for a chronic cough. Biopsy of the main bronchus shows stratified squamous epithelium. Which epithelium normally lines this site?
1. ANon-keratinised stratified squamous
2. BPseudostratified ciliated columnar
3. CTransitional
4. DSimple cuboidal
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Answer: B · Pseudostratified ciliated columnar
The trachea and bronchi are lined by pseudostratified ciliated columnar epithelium with goblet cells, the respiratory epithelium that moves mucus upwards. In smokers it is replaced by stratified squamous epithelium (squamous metaplasia), which resists irritation but loses the mucociliary escalator. Metaplasia is reversible, but persistent injury can lead through dysplasia to squamous cell carcinoma. Stopping smoking is therefore the key intervention.
- A: Non-keratinised stratified squamous epithelium is the abnormal finding here, not the normal lining.
- C: Transitional epithelium lines the urinary tract.
- D: Simple cuboidal epithelium lines the smallest bronchioles, not the main bronchus.
Question 5 · Medium
A 9-year-old boy has had a wet cough and nasal discharge since infancy, with repeated ear infections. HRCT shows bronchiectasis, and the chest X-ray shows the cardiac apex on the right. Nasal nitric oxide is very low. Which structure is most likely abnormal in his cells?
1. AActin core of the microvilli
2. BClaudins of the tight junctions
3. CType IV collagen of the basement membrane
4. DDynein arms of the ciliary axoneme
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Answer: D · Dynein arms of the ciliary axoneme
Recurrent sinusitis, otitis and bronchiectasis with situs inversus is Kartagener syndrome, a form of primary ciliary dyskinesia. The cilia have the 9+2 arrangement of microtubules, and the dynein arms that slide the doublets past each other are defective, most often the outer arms. Without effective beating, mucus is not cleared, and in the embryo the nodal cilia fail to set left-right asymmetry, so half the patients have situs inversus. Men are usually infertile because sperm flagella share the same structure.
- A: Microvilli have an actin core and increase surface area; they do not beat.
- B: Claudin defects affect paracellular transport, for example in the kidney, not mucus clearance.
- C: Type IV collagen defects cause Alport syndrome, with nephritis and deafness.
Question 6 · Medium
A 10-month-old girl has coarse facial features, marked gingival overgrowth, restricted joint movements and slow development. Lysosomal enzyme activity is very high in her plasma but low inside her cultured fibroblasts. In which organelle does her primary defect lie?
1. ALysosome
2. BRough endoplasmic reticulum
3. CGolgi apparatus
4. DPeroxisome
Answer and explanation in LearnFree account
Question 7 · Medium
An 8-year-old boy's school performance has fallen over a year, and he has become clumsy. He also has darkening of the skin and gums, and his morning cortisol is low with a high ACTH. MRI shows symmetrical white matter changes in the parieto-occipital regions, and plasma very-long-chain fatty acids are raised. Which organelle fails to break down these fatty acids?
1. APeroxisome
2. BLysosome
3. CMitochondrion
4. DSmooth endoplasmic reticulum
Answer and explanation in LearnFree account
Question 8 · Hard
A baby born to a healthy, consanguineous couple fails the newborn hearing screen, and testing confirms bilateral severe sensorineural deafness without other features. Genetic testing shows biallelic mutations in GJB2, the commonest single-gene cause of such non-syndromic deafness worldwide. The protein encoded by this gene forms which cell junction?
1. AAdherens junctions
2. BDesmosomes
3. CTight junctions
4. DGap junctions
Answer and explanation in LearnFree account

Histology and cell biology

A 45-year-old woman has painful oral erosions for two months, followed by flaccid blisters on her trunk that rupture easily. Gentle pressure on normal-looking skin makes the epidermis slide off. Antibodies against which cell junction cause this disease?

A 58-year-old man who has smoked bidis for 40 years undergoes bronchoscopy for a chronic cough. Biopsy of the main bronchus shows stratified squamous epithelium. Which epithelium normally lines this site?

A 9-year-old boy has had a wet cough and nasal discharge since infancy, with repeated ear infections. HRCT shows bronchiectasis, and the chest X-ray shows the cardiac apex on the right. Nasal nitric oxide is very low. Which structure is most likely abnormal in his cells?

A 10-month-old girl has coarse facial features, marked gingival overgrowth, restricted joint movements and slow development. Lysosomal enzyme activity is very high in her plasma but low inside her cultured fibroblasts. In which organelle does her primary defect lie?