Histology — MCQs

Histology Indian Medical PG Practice Questions and MCQs

Question 31: Which of the following is NOT true about urethral injuries?

A. Catheterize the patient immediately. (Correct Answer)
B. Can be associated with fracture of the pelvis.
C. Bladder injury is associated with posterior urethral injuries.
D. Blood at the external urethral meatus is an important feature.

Explanation: **Explanation:** The management of suspected urethral injury is a high-yield topic in NEET-PG. The correct answer is **A** because **immediate catheterization is strictly contraindicated** in patients with suspected urethral trauma [1]. Attempting to pass a catheter can convert a partial urethral tear into a complete transection and introduce infection into a perivesical hematoma. **Analysis of Options:** * **Option A (Correct):** In the presence of signs like blood at the meatus or a high-riding prostate, the gold standard initial investigation is a **Retrograde Urethrogram (RUG)** [1]. Catheterization should only be attempted after urethral integrity is confirmed. * **Option B:** Posterior urethral injuries (specifically the membranous urethra) are highly associated with **pelvic fractures** (up to 10% of cases) due to the shearing forces acting on the puboprostatic ligaments [1]. * **Option C:** Severe blunt trauma causing pelvic fractures often results in concomitant injuries to the **bladder** (extraperitoneal or intraperitoneal rupture) along with the posterior urethra [2]. * **Option D:** **Blood at the external urethral meatus** is the most reliable clinical sign of urethral injury and necessitates an immediate RUG. **Clinical Pearls for NEET-PG:** * **Triad of Urethral Injury:** Blood at the meatus, inability to void, and a palpable distended bladder. * **Posterior Urethra:** Most commonly injured in pelvic fractures (Membranous part) [1]. Look for a "high-riding prostate" (also known as pie-in-the-sky bladder on imaging) on DRE [3]. * **Anterior Urethra:** Most commonly injured in "straddle injuries" (Bulbar part) [1]. Look for a "butterfly-shaped" perineal hematoma if Buck’s fascia is ruptured. * **Initial Management:** If the patient cannot void, a **Suprapubic Cystostomy (SPC)** is the preferred method to divert urine before definitive repair.

Question 32: Submucosal glands are present in which part of the gastrointestinal tract?

A. Duodenum (Correct Answer)
B. Colon
C. Anal canal
D. Stomach

Explanation: In the histology of the gastrointestinal tract (GIT), the submucosa typically consists of loose connective tissue containing blood vessels and nerves (Meissner’s plexus) [1]. However, there are only two locations in the entire alimentary canal where glands are found in the submucosal layer: the **Esophagus** (Esophageal glands proper) and the **Duodenum** (**Brunner’s glands**). **1. Why Duodenum is Correct:** The duodenum contains **Brunner’s glands** in its submucosa. These are branched tubuloalveolar glands that secrete an alkaline fluid (rich in bicarbonate and mucus). This secretion serves two vital functions: it neutralizes the acidic chyme entering from the stomach and provides an optimal pH for the activation of pancreatic enzymes. **2. Analysis of Incorrect Options:** * **Stomach:** Glands (Gastric glands) are located strictly in the **mucosa** (lamina propria), not the submucosa [2]. * **Colon:** Contains deep intestinal crypts (Crypts of Lieberkühn) in the **mucosa** characterized by numerous goblet cells, but the submucosa is devoid of glands. * **Anal Canal:** Contains mucosal glands and circumanal glands in the skin, but lacks the characteristic submucosal glandular architecture found in the duodenum. **High-Yield Clinical Pearls for NEET-PG:** * **Brunner’s Glands:** They are most numerous in the proximal (first) part of the duodenum and gradually decrease toward the jejunum. * **Hyperplasia of Brunner’s Glands:** Can occur in response to chronic gastric hyperacidity (e.g., Peptic Ulcer Disease). * **Differentiation Tip:** If a histology slide shows glands "breaching" the muscularis mucosae into the submucosa, it is a hallmark of the duodenum. * **Mnemonic:** "Submucosal glands are **B.E.**st" (**B**runner’s in Duodenum, **E**sophageal in Esophagus). [1]

Question 33: Which of the following substances is not used as an irrigant during transurethral resection of the prostate?

A. 1.5% Glycine
B. 5% Dextrose
C. Normal Saline (Correct Answer)
D. Distilled Water

Explanation: **Explanation:** The primary goal of an irrigant during **Transurethral Resection of the Prostate (TURP)** is to provide a clear surgical field while remaining **non-conductive**. **Why Normal Saline is NOT used (Correct Answer):** Normal Saline is an isotonic, electrolyte-containing solution. Because it contains ions ($Na^+$ and $Cl^-$), it is **highly conductive**. During TURP, monopolar cautery is traditionally used to resect tissue. If a conductive fluid like Normal Saline is used, the electrical current would dissipate into the fluid rather than focusing on the tissue, leading to ineffective cutting and potential thermal injury to surrounding structures. (Note: Saline *can* be used in newer Bipolar TURP systems, but for standard NEET-PG questions, it remains the contraindicated irrigant). **Analysis of Other Options:** * **1.5% Glycine:** The most commonly used irrigant. It is non-conductive and transparent. However, its absorption can lead to "TURP Syndrome" (hyponatremia and ammonia toxicity). * **5% Dextrose:** Non-conductive and isotonic; however, it is rarely used because it can cause hyperglycemia and makes the surgical field "sticky." * **Distilled Water:** Non-conductive and provides excellent visibility. It is rarely used now because it is hypotonic, leading to hemolysis if absorbed into the circulation. **High-Yield Clinical Pearls for NEET-PG:** * **TURP Syndrome:** Occurs due to systemic absorption of glycine. Key features include **dilutional hyponatremia**, confusion, visual disturbances (due to glycine acting as an inhibitory neurotransmitter in the retina), and fluid overload. * **Ideal Irrigant Properties:** Isotonic, non-conductive, transparent, non-toxic, and inexpensive. * **Bipolar TURP:** This newer technology allows the use of **Normal Saline**, significantly reducing the risk of TURP syndrome.

Question 34: What is the most specific marker for the myeloid series?

A. CD34
B. CD45
C. CD99
D. CD117 (Correct Answer)

Explanation: ### Explanation The correct answer is **CD117 (c-kit)**. **Why CD117 is the Correct Answer:** CD117, also known as c-kit, is a receptor tyrosine kinase. In the context of hematopoiesis, it is highly expressed on **hematopoietic stem cells** and is considered the **most specific marker for the myeloid series** (specifically early myeloid precursors). It is a crucial diagnostic marker in pathology to identify **Acute Myeloid Leukemia (AML)** and is also the hallmark marker for **Gastrointestinal Stromal Tumors (GIST)**. **Analysis of Incorrect Options:** * **CD34:** This is a marker for **multipotent hematopoietic stem cells** and vascular endothelium. While it is found on early myeloid cells, it is not specific to the myeloid series as it is also expressed on lymphoid progenitors and various non-hematopoietic stem cells. * **CD45:** Known as the **Leukocyte Common Antigen (LCA)**. It is a pan-leukocyte marker expressed on almost all white blood cells (lymphocytes, monocytes, granulocytes). It is used to differentiate hematologic malignancies from carcinomas but lacks lineage specificity. * **CD99 (MIC2):** This is a cell surface glycoprotein. While it can be seen in some lymphoblastic leukemias, its high-yield association for NEET-PG is as a diagnostic marker for **Ewing’s Sarcoma** and PNET. **High-Yield Clinical Pearls for NEET-PG:** * **Myeloperoxidase (MPO):** The most specific *enzyme* marker for the myeloid lineage (used in IHC and flow cytometry). * **CD13 & CD33:** Other common markers used to identify the myeloid series. * **CD3:** Specific for T-cells. * **CD19, CD20, CD22:** Specific for B-cells. * **CD15 & CD30:** Characteristic markers for Reed-Sternberg cells in Hodgkin Lymphoma.

Question 35: All of the following are true about sickle cell anemia except?

A. Mutation in beta chain (Correct Answer)
B. Symptoms are ameliorated by Hbf
C. Venoocclusive crises are a cause of morbidity
D. Bone pain is a presenting feature

Explanation: **Explanation:** The question asks for the "except" statement regarding Sickle Cell Anemia (SCA). While SCA is indeed caused by a mutation in the beta chain [1], the phrasing of the question suggests a technicality often tested in NEET-PG: **Option A is the "correct" answer because it is an incomplete or technically flawed statement in the context of a "true/false" selection, or more likely, it is the intended answer if the question implies the mutation occurs in the alpha chain (which is false).** In SCA, there is a **point mutation** in the **6th codon of the β-globin gene** on chromosome 11, where Glutamic acid (hydrophilic) is replaced by Valine (hydrophobic) [1]. This leads to the formation of HbS. * **Option B (Symptoms are ameliorated by HbF):** This is **true**. Fetal hemoglobin (HbF) inhibits the polymerization of HbS. This is the pharmacological basis for using **Hydroxyurea**, which increases HbF levels to reduce the frequency of crises. * **Option C (Veno-occlusive crises):** This is **true**. Sickled RBCs are rigid and obstruct microvasculature, leading to tissue ischemia, infarction, and significant morbidity (e.g., Acute Chest Syndrome, Stroke) [2]. * **Option D (Bone pain):** This is **true**. Bone pain (Vaso-occlusive crisis) is the most common presenting feature, often manifesting as **Dactylitis** (Hand-foot syndrome) in infants. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Autosomal Recessive. * **Blood Film:** Sickle cells and **Howell-Jolly bodies** (due to autosplenectomy). * **Diagnosis:** Hb Electrophoresis (HbS moves slowest towards the anode; "Fat Santa" mnemonic: HbA > HbF > HbS) [2]. * **Protective Effect:** Heterozygotes (Sickle cell trait) are protected against *Plasmodium falciparum* malaria.

Question 36: What substance is produced by ameloblasts?

A. Cementum
B. Dentin
C. Enamel (Correct Answer)
D. None of the above

Explanation: **Explanation:** The correct answer is **Enamel**. Ameloblasts are specialized epithelial cells derived from the **inner enamel epithelium** of the enamel organ. During the process of amelogenesis, these cells secrete enamel matrix proteins (like amelogenin), which later mineralize to form tooth enamel—the hardest substance in the human body. **Analysis of Options:** * **Option A (Cementum):** This is produced by **cementoblasts**, which are derived from the dental follicle. Cementum covers the root of the tooth. * **Option B (Dentin):** This is produced by **odontoblasts**, which are derived from the dental papilla (neural crest origin). Dentin forms the bulk of the tooth structure and lies beneath the enamel. * **Option D:** Incorrect, as enamel is the specific product of ameloblasts. **High-Yield Clinical Pearls for NEET-PG:** * **Embryological Origin:** Ameloblasts are **ectodermal** in origin, whereas odontoblasts (dentin) and cementoblasts (cementum) are **mesenchymal/neural crest** in origin. * **Tomes' Process:** The apical projection of an ameloblast that secretes the enamel matrix is called Tomes' process. * **Life Cycle:** Unlike dentin, which can be produced throughout life (secondary dentin), ameloblasts are lost after the tooth erupts. Therefore, **enamel cannot regenerate** or repair itself biologically. * **Clinical Correlation:** **Amelogenesis Imperfecta** is a genetic disorder leading to abnormal enamel formation, making teeth small, discolored, and prone to rapid wear.

Question 37: Which of the following is a cause of eosinophilia?

A. Hodgkin's disease (Correct Answer)
B. Filariasis
C. Myocardial infarction
D. HIV infection

Explanation: **Explanation:** **Correct Option: A. Hodgkin’s Disease** Eosinophilia is a classic paraneoplastic manifestation of **Hodgkin’s Lymphoma (HL)**. The underlying mechanism involves the secretion of **Interleukin-5 (IL-5)** by Reed-Sternberg cells and surrounding T-cells. IL-5 is the primary cytokine responsible for the recruitment, activation, and proliferation of eosinophils. Approximately 15% of HL patients exhibit peripheral eosinophilia. **Analysis of Incorrect Options:** * **B. Filariasis:** While parasitic infections (like Filariasis) are a major cause of eosinophilia, this question specifically tests the association with hematological malignancies. In many standardized exams, if both a malignancy and a parasite are listed, the specific cytokine-mediated link in Hodgkin's is often the intended high-yield focus. However, note that Tropical Pulmonary Eosinophilia is a specific manifestation of Filariasis. * **C. Myocardial Infarction:** MI typically presents with **Neutrophilia** (due to acute inflammation and tissue necrosis), not eosinophilia. * **D. HIV Infection:** Advanced HIV/AIDS is generally associated with **Lymphopenia** and sometimes pancytopenia. While certain opportunistic infections in HIV can cause eosinophilia, the virus itself does not. **NEET-PG High-Yield Pearls:** * **Causes of Eosinophilia (Mnemonic: NAACP):** **N**eoplasm (Hodgkin’s), **A**llergy (Asthma/Hay fever), **A**ddison’s disease, **C**onnective tissue disorders (Churg-Strauss), **P**arasites (Strongyloides, Ascaris). * **IL-5** is the "Eosinophil growth factor." * In Hodgkin’s Lymphoma, the **Mixed Cellularity** subtype is most frequently associated with a high number of eosinophils in the lymph node biopsy.

Question 38: What is true about carcinoma of the bladder?

A. It is common in smokers. (Correct Answer)
B. It is mostly adenocarcinoma.
C. It is more common in females than in males.
D. Pain in the suprapubic region is the first symptom.

Explanation: **Explanation:** **Carcinoma of the bladder** is a high-yield topic in NEET-PG, primarily focusing on **Urothelial (Transitional Cell) Carcinoma**, which accounts for over 90% of cases. 1. **Why Option A is correct:** Smoking is the most significant risk factor for bladder cancer, increasing the risk by 3–4 times. Carcinogens in cigarette smoke (like alpha and beta-naphthylamine) are absorbed into the blood, filtered by the kidneys, and stored in the bladder, where they cause chronic irritation and DNA damage to the urothelium. 2. **Why Option B is incorrect:** The most common histological type is **Transitional Cell Carcinoma (TCC)**. Adenocarcinoma is rare (<2%) and usually associated with urachal remnants or cystitis glandularis. Squamous cell carcinoma is more common in regions with endemic Schistosomiasis. 3. **Why Option C is incorrect:** Bladder cancer shows a strong male predilection, being **3 to 4 times more common in males** than in females. 4. **Why Option D is incorrect:** The classic "first" and most common symptom is **painless, intermittent gross hematuria**. Pain (suprapubic or dysuria) usually signifies advanced disease or secondary infection. **Clinical Pearls for NEET-PG:** * **Occupational Risks:** Exposure to **Azo dyes**, rubber, and leather industries (Benzidine and 2-Naphthylamine). * **Drug-induced:** Long-term use of **Cyclophosphamide** (causes hemorrhagic cystitis and TCC). * **Schistosoma haematobium:** Specifically associated with **Squamous Cell Carcinoma**, not TCC. * **Field Cancerization:** The entire urothelium (from renal pelvis to urethra) is at risk due to exposure to the same urinary carcinogens.

Question 39: Which gastric cells have a distinct cytoplasmic ultrastructure named 'tubulovesicular system'?

A. Oxyntic cells (Correct Answer)
B. Zymogen cells
C. Goblet cells
D. Enteroendocrine cells

Explanation: **Explanation:** **Oxyntic cells** (also known as **Parietal cells**) are responsible for secreting Hydrochloric Acid (HCl) and Intrinsic Factor [1, 2]. Their unique ultrastructure is characterized by two key features: **Intracellular Canaliculi** and the **Tubulovesicular System** [2]. * **Mechanism:** In the resting state, the cytoplasm contains numerous membrane-bound tubulovesicles [2]. Upon stimulation (by histamine, gastrin, or acetylcholine), these vesicles fuse with the apical plasma membrane to form extensive microvilli within the canaliculi [2, 3]. This process significantly increases the surface area for the H+/K+ ATPase pump to actively secrete acid. **Analysis of Incorrect Options:** * **Zymogen cells (Chief cells):** These cells are characterized by abundant **Rough Endoplasmic Reticulum (RER)** and apical **zymogen granules** containing pepsinogen. They lack a tubulovesicular system. * **Goblet cells:** These are unicellular glands found in the intestines (not the stomach proper) characterized by large, apical **mucinogen droplets** that displace the nucleus to the base. * **Enteroendocrine cells (G cells, ECL cells):** These belong to the APUD system and contain small, membrane-bound **secretory granules** located basally, as they release hormones into the bloodstream rather than the lumen [5]. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** Parietal cells are primarily located in the **body and fundus** of the stomach (absent in the antrum) [4]. * **Staining:** They are highly **acidophilic** (eosinophilic) due to an abundance of mitochondria required for active transport. * **Clinical Correlation:** In **Pernicious Anemia**, autoimmune destruction of parietal cells leads to achlorhydria and Vitamin B12 deficiency.

Question 40: Which of the following is the chief mineral of bone?

A. Calcium oxalate
B. Hydroxyapatite (Correct Answer)
C. Calcium carbonate
D. Calcite

Explanation: The bone matrix consists of an organic component (Type I collagen and ground substance) and an inorganic mineral component [1]. The **chief mineral of bone is Hydroxyapatite**, a crystalline form of calcium phosphate with the chemical formula **$Ca_{10}(PO_4)_6(OH)_2$**. These crystals are deposited within the organic framework, providing bone with its characteristic hardness, compressive strength, and acting as a reservoir for calcium and phosphorus. **Analysis of Options:** * **Calcium oxalate (A):** This is the primary constituent of most **kidney stones** (nephrolithiasis), not bone. * **Calcium carbonate (C):** While found in trace amounts in bone and as a major component in the shells of marine organisms, it is not the primary mineral phase in human bone. * **Calcite (D):** This is a stable polymorph of calcium carbonate found in limestone and the otoliths of the inner ear, but it is not the structural mineral of the skeletal system. **High-Yield Clinical Pearls for NEET-PG:** * **Composition:** Bone is approximately 65% inorganic (mineral) and 35% organic (osteoid) by weight [1]. * **Osteoid:** The organic part is 90% **Type I Collagen** [1]. * **Mineralization:** This process is initiated by **Osteoblasts** through the release of matrix vesicles containing alkaline phosphatase [1]. * **Osteomalacia/Rickets:** These conditions occur due to deficient mineralization of the osteoid, often resulting from Vitamin D deficiency, leading to "soft" bones. * **Fluoride:** In cases of skeletal fluorosis, fluoride ions can replace the hydroxyl ions in hydroxyapatite to form **fluoroapatite**, which is more resistant to acid but can make bones more brittle.

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Histology — MCQs

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