Histology — MCQs

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?

Q369Medium

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

Q370

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

Histology Indian Medical PG Practice Questions and MCQs

Question 361: Reticulocytes are stained by which of the following dyes?

A. Methyl violet
B. Brilliant cresyl blue (Correct Answer)
C. Sudan black
D. Indigo carmine

Explanation: **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].

Question 362: Which of the following is the epithelial lining of the vagina?

A. Stratified squamous non-keratinized (Correct Answer)
B. Columnar
C. Stratified squamous keratinized
D. Cuboidal

Explanation: 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].

Question 363: What type of epithelium lines the cornea?

A. Stratified squamous non-keratinizing (Correct Answer)
B. Stratified squamous keratinizing
C. Columnar keratinized
D. Columnar non-keratinized

Explanation: **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.

Question 364: Which of the following inclusions are seen on Romanowsky stain?

A. Cabot rings
B. Basophilic stippling
C. Howell-Jolly bodies
D. All of the above (Correct Answer)

Explanation: **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].

Question 365: Transitional epithelium is present in which of the following locations?

A. Renal pelvis (Correct Answer)
B. Loop of Henle
C. Terminal part of urethra
D. Proximal convoluted tubule (PCT)

Explanation: **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.

Question 366: A 60-year-old male presented with dysphagia. A mucosal biopsy was performed. What is the most likely finding on histology?

A. Squamous metaplasia
B. Columnar metaplasia (Correct Answer)
C. Anaplasia
D. Connective tissue metaplasia

Explanation: ### 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.

Question 367: Which of the following is an absolute indication for surgery in cases of benign prostatic hyperplasia?

A. Bilateral hydroureteronephrosis
B. Nocturnal frequency
C. Recurrent urinary tract infection (Correct Answer)
D. Voiding bladder pressures > 50 cm of water

Explanation: **Explanation:** The management of Benign Prostatic Hyperplasia (BPH) ranges from watchful waiting to surgical intervention [1]. While many patients are managed medically (Alpha-blockers, 5-Alpha reductase inhibitors), specific complications signify the failure of conservative management and serve as **absolute indications** for surgery (usually TURP). **Why Option C is Correct:** **Recurrent urinary tract infections (UTIs)** caused by significant post-void residual urine are a definitive indication for surgery [1]. Chronic stasis of urine acts as a culture medium for bacteria; if the underlying obstruction is not removed, the patient remains at risk for urosepsis and chronic pyelonephritis [2], [4]. **Analysis of Incorrect Options:** * **Option A (Bilateral hydroureteronephrosis):** While this indicates advanced obstruction, it is the resulting **renal insufficiency (azotemia)** that is considered the absolute indication. Hydronephrosis alone may sometimes be monitored if renal function remains stable, though it often leads to surgery. * **Option B (Nocturnal frequency):** This is a Lower Urinary Tract Symptom (LUTS) [1]. While bothersome and a common reason patients seek help, it is a **relative indication**. Surgery is only considered if the symptoms significantly impair the patient's quality of life and fail medical therapy [3]. * **Option D (Voiding bladder pressures > 50 cm H2O):** This is a urodynamic finding indicating bladder outlet obstruction, but it is not an absolute indication for surgery on its own without clinical complications [1]. **High-Yield Clinical Pearls for NEET-PG:** The absolute indications for surgery in BPH (mnemonic: **"H-R-R-S-B"**) include: 1. **H**ydronephrosis with **Renal failure** (Azotemia). 2. **R**efractory urinary retention (failed at least one attempt at catheter removal). 3. **R**ecurrent Urinary Tract Infections. 4. **S**tones in the bladder (vesical calculi). 5. **B**leeding (Recurrent gross hematuria).

Question 368: 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?

A. Primary spermatocyte
B. Secondary spermatocyte
C. Spermatid
D. Spermatogonia (Correct Answer)

Explanation: ### Explanation The process of **spermatogenesis** occurs within the seminiferous tubules, organized in a highly structured centripetal manner (from the basement membrane toward the lumen) [3]. **1. Why Spermatogonia is Correct:** Spermatogonia are the **undifferentiated stem cells** of the male germline [3]. They are located in the **basal compartment**, resting directly on the **basal lamina** (basement membrane) [1]. These cells undergo mitosis to either maintain the stem cell population (Type A) or differentiate into cells that will enter meiosis (Type B). Because they are the starting point of spermatogenesis, they are the outermost germ cells [2]. **2. Why the Other Options are Incorrect:** * **Primary Spermatocytes (A):** These are derived from Type B spermatogonia [3]. They move away from the basal lamina, cross the blood-testis barrier, and enter the adluminal compartment to undergo Meiosis I [1]. * **Secondary Spermatocytes (B):** These are the products of Meiosis I. They are located closer to the lumen than primary spermatocytes and have a very short lifespan. * **Spermatids (C):** These are haploid cells resulting from Meiosis II. They are found in the most superficial layers of the seminiferous epithelium, often embedded in the apical processes of Sertoli cells, just before being released into the lumen as spermatozoa [2]. **3. NEET-PG High-Yield Pearls:** * **Blood-Testis Barrier:** Formed by **tight junctions between Sertoli cells** [1]. It separates the basal compartment (containing spermatogonia) from the adluminal compartment (containing meiotic cells) [1]. * **Sertoli Cells:** Also known as "nurse cells," they rest on the basal lamina and extend to the lumen [1]. They are **non-germinal** cells. * **Spermiogenesis:** The morphological transformation of a round spermatid into a motile spermatozoon (no cell division involved). * **Clinical Correlation:** In "Sertoli cell-only syndrome," germ cells (including spermatogonia) are entirely absent, leading to azoospermia and infertility.

Question 369: A 70-year-old man presents with urinary retention and back pain. Which investigation should be performed?

A. Serum acid phosphatase (Correct Answer)
B. Serum calcium
C. Serum alkaline phosphatase
D. Serum electrophoresis

Explanation: **Explanation:** The clinical presentation of a 70-year-old man with **urinary retention** (suggestive of prostatic enlargement) and **back pain** (suggestive of vertebral metastasis) is a classic scenario for **Metastatic Carcinoma of the Prostate**. 1. **Why Serum Acid Phosphatase (SAP) is correct:** Prostatic tissue, especially cancerous cells, contains high concentrations of the enzyme **Prostatic Acid Phosphatase (PAP)**. When the carcinoma breaches the prostatic capsule or metastasizes (typically to the bone), levels of SAP rise significantly. While PSA (Prostate-Specific Antigen) is the modern gold standard for screening, SAP remains a high-yield classic marker for assessing **extra-capsular extension and bony metastasis** in prostate cancer. 2. **Why the other options are incorrect:** * **Serum Calcium:** While bone metastasis can alter calcium levels, it is non-specific and not a primary diagnostic marker for prostate cancer. * **Serum Alkaline Phosphatase (ALP):** ALP levels rise in **osteoblastic** (bone-forming) lesions. While prostate cancer causes osteoblastic metastases, ALP is also elevated in liver diseases and other bone pathologies, making it less specific than SAP for the prostate. * **Serum Electrophoresis:** This is the investigation of choice for **Multiple Myeloma** (characterized by an M-spike). While myeloma also causes back pain in the elderly, it typically presents with "punched-out" osteolytic lesions rather than the osteoblastic lesions seen in prostate cancer. **NEET-PG High-Yield Pearls:** * **Prostate Cancer Metastasis:** Most common site is the **lumbar spine** via the **Batson’s venous plexus** (valveless vertebral venous plexus). * **Nature of Lesion:** Prostate cancer typically produces **Osteoblastic** (sclerotic) metastases, unlike most other cancers which are osteolytic. * **Tartrate-Resistant Acid Phosphatase (TRAP):** A specific stain used for Hairy Cell Leukemia, not to be confused with Prostatic Acid Phosphatase.

Question 370: Histological section is given below. Identify the marked cell. ![img-34.jpeg](img-34.jpeg)

A. Purkinje cell (Correct Answer)
B. Granular cell
C. Stellate cell
D. Basket cell

Explanation: ***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.

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Histology — MCQs

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