Histology Practice Questions

Q: Reticulocytes are stained by which of the following dyes?

Brilliant cresyl blue. **Explanation:** Reticulocytes are immature red blood cells that contain residual ribosomal RNA (rRNA). Because these cells lack a nucleus but still possess organelles, they cannot be identified using routine Romanowsky stains (like Leishman or Giemsa), which only show them as slightly larger, bluish cells (polychromasia). **1. Why Brilliant Cresyl Blue is correct:** To visualize the network of rRNA (the "reticulum"), **supravital staining** is required. This involves staining living cells before they are fixed. **Brilliant cresyl blue** (or New Methylene Blue) is a basic dye that reacts with the acidic rRNA, causing it to precipitate into a visible blue, granular filament or network. This allows for an accurate reticulocyte count, which is a key indicator of bone marrow erythropoietic activity. **2. Analysis of Incorrect Options:** * **Methyl violet:** Primarily used as a histological stain and for staining **Heinz bodies** (denatured hemoglobin) in G6PD deficiency [1]. * **Sudan black:** A lipid-soluble dye used to stain neutral triglycerides and lipids. In hematology, it is used to differentiate **Acute Myeloid Leukemia (AML)** from ALL by staining myeloblasts. * **Indigo carmine:** A dye used primarily in surgery and urology to highlight the urinary tract or to detect amniotic fluid leaks; it is not used for blood cell morphology. **Clinical Pearls for NEET-PG:** * **Supravital Stains:** Remember the mnemonic **"RNB"** (Reticulocytes, New Methylene Blue, Brilliant Cresyl Blue). * **Reticulocyte Count:** It is the best indicator of **effective erythropoiesis**. A high count is seen in hemolytic anemias, while a low count suggests bone marrow failure (e.g., Aplastic anemia). * **Heinz Bodies:** These also require supravital stains (like Crystal Violet) but appear as single coccoid granules at the cell periphery, unlike the network seen in reticulocytes [1].

Q: Which of the following is the epithelial lining of the vagina?

Stratified squamous non-keratinized. The vagina is a muscular canal lined by **Stratified Squamous Non-keratinized Epithelium**. This histological structure is specifically adapted to withstand mechanical stress and friction during coitus and childbirth. **Why Option A is correct:** The multiple layers of squamous cells provide a protective barrier. Under the influence of estrogen, these cells accumulate **glycogen**. When these cells desquamate, the glycogen is fermented by commensal bacteria (*Döderlein’s bacilli* / Lactobacillus) into **lactic acid**, maintaining an acidic vaginal pH (3.8–4.5), which inhibits the growth of pathogens. **Why other options are incorrect:** * **B. Columnar:** This lining is found in the endocervix and the rest of the female reproductive tract (uterus and fallopian tubes) [1]. The transition from columnar to squamous epithelium occurs at the **Squamocolumnar Junction** (Transformation Zone) of the cervix [1]. * **C. Stratified squamous keratinized:** This is found in the skin (epidermis) [2]. Keratin provides a waterproof, protective layer against desiccation, which is unnecessary in the moist environment of the vagina. * **D. Cuboidal:** Simple cuboidal epithelium is typically found in glandular ducts or the germinal epithelium of the ovary, not in areas prone to high friction. **High-Yield Clinical Pearls for NEET-PG:** * **Embryology:** The upper 1/3rd of the vagina is derived from **Müllerian ducts** (Mesoderm), while the lower 2/3rds is derived from the **Urogenital sinus** (Endoderm) [2]. * **Vaginal pH:** It is acidic during reproductive years but becomes neutral/alkaline before puberty and after menopause due to low estrogen levels. * **Cytology:** The cells seen on a Pap smear from the ectocervix/vagina are these stratified squamous cells [2].

Q: What type of epithelium lines the cornea?

Stratified squamous non-keratinizing. **Explanation:** The **cornea** is the transparent anterior part of the eye [1]. Its outermost layer, the corneal epithelium, is composed of **Stratified Squamous Non-Keratinizing Epithelium**. **Why Option A is Correct:** The corneal epithelium consists of 5–6 layers of cells. The basal layer is columnar, the middle layers are wing cells, and the superficial layers are flattened (squamous). It is **non-keratinizing** to maintain transparency and ensure a smooth, moist refractive surface [1]. The presence of keratin would make the cornea opaque and dry, obstructing vision [2]. **Why the Other Options are Incorrect:** * **Option B (Stratified squamous keratinizing):** This is found in the **epidermis of the skin**. Keratin provides a waterproof, protective barrier but is opaque. If the cornea undergoes keratinization (e.g., in severe Vitamin A deficiency), it leads to blindness [2]. * **Options C & D (Columnar):** While the basal layer of the cornea is columnar (for regeneration), the overall classification of a stratified epithelium is always based on the shape of the **superficial layer**, which is squamous in the cornea. **High-Yield NEET-PG Pearls:** 1. **Regeneration:** The corneal epithelium has a high turnover rate (approx. 7 days). It is replenished by stem cells located at the **Limbal Basal Layer** [2] (the junction between the cornea and sclera). 2. **Bowman’s Membrane:** Located just beneath the epithelium; it does not regenerate if damaged, leading to permanent scarring [2]. 3. **Clinical Correlation:** **Vitamin A deficiency** causes squamous metaplasia and keratinization of the cornea (Xerophthalmia), leading to Bitot’s spots and eventually keratomalacia. 4. **Nerve Supply:** The cornea is one of the most sensitive tissues in the body, supplied by the **Ophthalmic nerve (V1)** via long ciliary nerves.

Q: Which of the following inclusions are seen on Romanowsky stain?

All of the above. **Explanation:** The correct answer is **D. All of the above**. Romanowsky-based stains (such as **Leishman, Wright, and Giemsa**) are the standard polychromatic stains used in hematology to visualize blood cells and their intracellular inclusions. These stains contain a mixture of Methylene blue (basic) and Eosin (acidic), which allows for the differentiation of nuclear and cytoplasmic components [1]. * **Cabot rings:** These are thin, red-violet, loop-shaped or figure-of-eight structures representing remnants of the mitotic spindle. They are clearly visible on Romanowsky stains and are typically seen in megaloblastic anemia or lead poisoning. * **Basophilic stippling:** These are fine or coarse deep-blue granules distributed throughout the RBC, representing unstable clusters of ribosomes (RNA). They are a hallmark of lead poisoning and sideroblastic anemia. * **Howell-Jolly bodies:** These are small, round, purple-to-black inclusions representing nuclear remnants (DNA) [2]. They are usually removed by the spleen; thus, their presence on a peripheral smear is a high-yield sign of **asplenia or hyposplenism** (e.g., post-splenectomy or Sickle Cell Anemia) [2]. **Clinical Pearls for NEET-PG:** 1. **Heinz Bodies:** These are NOT seen on Romanowsky stains. They require **Supravital stains** (like Crystal Violet or New Methylene Blue) and represent denatured hemoglobin (seen in G6PD deficiency) [2]. 2. **Reticulocytes:** While they show "polychromasia" on Romanowsky stains, the characteristic reticular network is only visible with **Supravital stains**. 3. **Pappenheimer bodies:** These are siderotic (iron) granules seen on Romanowsky stains but confirmed using **Perls' Prussian Blue** reaction [2].

Q: Transitional epithelium is present in which of the following locations?

Renal pelvis. **Explanation:** **Transitional epithelium (Urothelium)** is a specialized stratified epithelium unique to the urinary tract [1]. Its primary function is to provide a waterproof barrier while allowing for significant distension and contraction as the volume of urine changes. **Why the Correct Answer is Right:** The **Renal Pelvis** is the beginning of the "excretory" portion of the urinary system. Transitional epithelium lines the entire urinary tract from the **renal calyces** (major and minor) to the **renal pelvis**, **ureters**, **urinary bladder**, and the **proximal part of the urethra** [1]. Its "umbrella cells" (superficial layer) are specifically adapted to resist the osmotic pressure of concentrated urine. **Analysis of Incorrect Options:** * **Loop of Henle:** Lined by **simple squamous epithelium** (thin limbs) and **simple cuboidal epithelium** (thick limbs). These are involved in active transport and passive diffusion, not distension. * **Terminal part of urethra:** In both males and females, the distal-most part of the urethra transitions from transitional/pseudostratified columnar to **non-keratinized stratified squamous epithelium** as it nears the external orifice. * **Proximal Convoluted Tubule (PCT):** Lined by **simple cuboidal epithelium with a prominent brush border** (microvilli) to maximize surface area for reabsorption. **High-Yield Clinical Pearls for NEET-PG:** * **Umbrella Cells:** The topmost layer of transitional epithelium contains "facet cells" or "umbrella cells," which may be binucleated and contain **uroplakin** proteins that form a barrier against urine toxicity [1]. * **Schistosomiasis:** Chronic infection can cause squamous metaplasia of the bladder's transitional epithelium, leading to **Squamous Cell Carcinoma**. * **Key Locations:** Remember the "Calyces to Urethra" rule—if it stores or transports urine (but doesn't filter/modify it), it is likely transitional.

Q: A 60-year-old male presented with dysphagia. A mucosal biopsy was performed. What is the most likely finding on histology?

Columnar metaplasia. ### Explanation **Correct Option: B. Columnar Metaplasia** The clinical presentation of dysphagia in an elderly male, often associated with chronic gastroesophageal reflux disease (GERD), points toward **Barrett’s Esophagus**. In this condition, the normal **stratified squamous epithelium** of the lower esophagus undergoes adaptation due to chronic acid irritation, transforming into **simple columnar epithelium** (often with goblet cells). This process is a classic example of **metaplasia**, where one adult cell type is replaced by another adult cell type better suited to withstand the environmental stress. **Analysis of Incorrect Options:** * **A. Squamous metaplasia:** This occurs when columnar epithelium changes to squamous (e.g., in the respiratory tract of smokers or the endocervix). Since the esophagus is already lined by squamous cells, this is incorrect. * **C. Anaplasia:** This refers to a lack of differentiation and is a hallmark of malignancy (cancer), not a reversible adaptive change like metaplasia. * **D. Connective tissue metaplasia:** This involves the formation of cartilage, bone, or adipose tissue in areas where they don't belong (e.g., Myositis Ossificans). It does not occur in the esophageal mucosa. **NEET-PG High-Yield Pearls:** * **Definition:** Metaplasia is a reversible change; however, if the stimulus persists, it can progress to **dysplasia** and eventually **adenocarcinoma**. * **Barrett’s Esophagus:** Defined histologically by the presence of **intestinal metaplasia** (specifically identifying **Goblet cells** on H&E or Alcian Blue stain). * **Most common site:** Squamous metaplasia is the most common type of epithelial metaplasia overall, but columnar metaplasia is the specific answer for Barrett's Esophagus.

Q: Histological section is given below. Identify the marked cell. ![img-34.jpeg](img-34.jpeg)

Purkinje cell. ***Purkinje cell*** - The marked cell is a **Purkinje cell**, identified by its large, **flask-shaped** (pyriform) body and its characteristic location in the cerebellar cortex. - These neurons form a distinct single layer, the **Purkinje cell layer**, situated between the outer, less cellular **molecular layer** and the inner, densely packed **granular layer**. *Stellate cell* - **Stellate cells** are small, star-shaped inhibitory interneurons located within the superficial part of the **molecular layer**; they are not the large, flask-shaped cells shown. - They are significantly smaller than Purkinje cells and do not form a distinct, single-cell-thick layer. *Basket cell* - **Basket cells** are inhibitory interneurons found in the deeper part of the **molecular layer**, close to the Purkinje cells. - Although they synapse on Purkinje cells by forming a 'basket' of fibers around the soma, the arrow is pointing to the large Purkinje cell body itself, not the smaller basket cell. *Granular cell* - **Granular cells** are the very small, densely packed neurons with dark-staining nuclei that form the **granular layer**, which is the dark purple layer at the bottom of the image. - The marked cell is clearly much larger than a granular cell and is located in the layer just above the granular layer.

Question 1

Reticulocytes are stained by which of the following dyes?

Accepted Answer

Brilliant cresyl blue

Answer

Methyl violet

Answer

Sudan black

Answer

Indigo carmine

Question 2

Which of the following is the epithelial lining of the vagina?

Accepted Answer

Stratified squamous non-keratinized

Answer

Columnar

Answer

Stratified squamous keratinized

Answer

Cuboidal

Question 3

What type of epithelium lines the cornea?

Accepted Answer

Stratified squamous non-keratinizing

Answer

Stratified squamous keratinizing

Answer

Columnar keratinized

Answer

Columnar non-keratinized

Question 4

Which of the following inclusions are seen on Romanowsky stain?

Accepted Answer

All of the above

Answer

Cabot rings

Answer

Basophilic stippling

Answer

Howell-Jolly bodies

Question 5

Transitional epithelium is present in which of the following locations?

Accepted Answer

Renal pelvis

Answer

Loop of Henle

Answer

Terminal part of urethra

Answer

Proximal convoluted tubule (PCT)

Question 6

A 60-year-old male presented with dysphagia. A mucosal biopsy was performed. What is the most likely finding on histology?

Accepted Answer

Columnar metaplasia

Answer

Squamous metaplasia

Answer

Anaplasia

Answer

Connective tissue metaplasia

Question 7

Which of the following is an absolute indication for surgery in cases of benign prostatic hyperplasia?

Accepted Answer

Recurrent urinary tract infection

Answer

Bilateral hydroureteronephrosis

Answer

Nocturnal frequency

Answer

Voiding bladder pressures > 50 cm of water

Question 8

A 35-year-old male presents for an infertility evaluation. A biopsy of his testis is performed to assess sperm production and maturation. A microscopic section reveals only a few germ cells near the basal lamina in the seminiferous tubule. Which of the following cells is the germ cell closest to the basal lamina in the seminiferous tubule?

Accepted Answer

Spermatogonia

Answer

Primary spermatocyte

Answer

Secondary spermatocyte

Answer

Spermatid

Question 9

A 70-year-old man presents with urinary retention and back pain. Which investigation should be performed?

Accepted Answer

Serum acid phosphatase

Answer

Serum calcium

Answer

Serum alkaline phosphatase

Answer

Serum electrophoresis

Question 10

Histological section is given below. Identify the marked cell. ![img-34.jpeg](img-34.jpeg)

Accepted Answer

Purkinje cell

Answer

Granular cell

Answer

Stellate cell

Answer

Basket cell

Histology — MCQs

Histology — MCQs

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