Inflammation and Repair — MCQs

Inflammation and Repair Indian Medical PG Practice Questions and MCQs

Question 91: A 50-year-old alcoholic is rushed to the hospital with bleeding esophageal varices and expires. At autopsy, the patient's protruding abdomen is found to contain a large volume of serous fluid. What is the appropriate term used to describe this fluid?

A. Ascites (Correct Answer)
B. Exudate
C. Hemorrhage
D. Hydrothorax

Explanation: ### Explanation **Correct Answer: A. Ascites** The patient presents with classic signs of **portal hypertension** secondary to alcoholic liver cirrhosis (evidenced by esophageal varices and a protruding abdomen) [2]. In cirrhosis, portal hypertension and hypoalbuminemia (decreased oncotic pressure) lead to the accumulation of **transudative fluid** within the peritoneal cavity [1], [4]. The specific clinical term for the accumulation of serous fluid in the abdominal cavity is **Ascites** [4]. **Analysis of Incorrect Options:** * **B. Exudate:** This refers to inflammatory fluid with high protein content and cellular debris, typically caused by increased vascular permeability (e.g., peritonitis). The fluid in cirrhosis is a **transudate** (low protein, low specific gravity) caused by hydrostatic and oncotic pressure imbalances [4]. * **C. Hemorrhage:** This implies the escape of blood from the vascular system. While the patient had bleeding varices [2], the "large volume of serous fluid" in the abdomen refers to the clear, straw-colored fluid of ascites, not active bleeding into the peritoneum (hemoperitoneum). * **D. Hydrothorax:** This is the term for the accumulation of serous fluid in the **pleural cavity** (chest), not the abdominal cavity [4]. **NEET-PG High-Yield Pearls:** * **Starling’s Forces:** Edema/Ascites in cirrhosis is multifactorial: ↑ Hydrostatic pressure (portal HTN) + ↓ Plasma oncotic pressure (hypoalbuminemia) + Na/Water retention (RAAS activation) [1], [3]. * **SAAG Score:** In clinical practice, the **Serum-Ascites Albumin Gradient (SAAG)** is used to distinguish causes. A SAAG **>1.1 g/dL** indicates portal hypertension (transudate). * **Morphology:** On gross examination, ascitic fluid is typically serous (clear/straw-colored). If it appears milky, it is termed **chylous ascites** (lymphatic obstruction). **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 396-398. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Liver And Biliary System Disease, pp. 383-384. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Liver and Gallbladder, pp. 835-836. [4] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 126-127.

Question 92: When is the maximum collagen content of wound tissue?

A. Between the 3rd to 5th day
B. Between the 6th to 17th day
C. Between the 17th to 21st day (Correct Answer)
D. None of the above

Explanation: **Explanation:** The correct answer is **C (Between the 17th to 21st day)**. This timing corresponds to the peak of the proliferative phase and the transition into the remodeling phase of wound healing. **1. Why Option C is correct:** During wound healing, collagen synthesis begins as early as day 3, but it reaches its **maximal rate** and **peak accumulation** between the end of the second week and the end of the third week (roughly days 14–21). At this stage, the balance between collagen synthesis and degradation (by matrix metalloproteinases) shifts, leading to the highest net content of collagen in the granulation tissue [1]. **2. Why other options are incorrect:** * **Option A (3rd to 5th day):** This is the early proliferative phase. While fibroblasts are migrating to the site and beginning to secrete Type III collagen, the total content is still very low [1]. * **Option B (6th to 17th day):** While collagen is rapidly accumulating during this window, it has not yet reached its peak concentration. The "plateau" of maximum content typically occurs toward the end of this period and into the third week [1]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Collagen Type Switch:** Initially, **Type III collagen** (embryonic/granulation tissue) is predominant. During remodeling, it is replaced by **Type I collagen**, which provides greater tensile strength. * **Tensile Strength Milestones:** * At 1 week (sutures removed): ~10% of original strength [2]. * At 3 months: ~70–80% of original strength (this is usually the maximum strength a scar achieves; it rarely reaches 100%) [2]. * **Vitamin C:** Essential for the hydroxylation of proline and lysine residues; deficiency leads to scurvy and poor wound healing due to defective collagen cross-linking [3]. * **Zinc:** A necessary cofactor for Collagenase (MMP), which is vital for the remodeling phase. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 117-119. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 119-121. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 116-117.

Question 93: What is diapedesis?

A. Immigration of leucocytes through the basement membrane
B. Immigration of leucocytes through the vessel wall to the site of inflammation (Correct Answer)
C. Aggregation of platelets at the site of bleeding
D. Autodigestion of cells

Explanation: ### Explanation **Diapedesis** (also known as **transmigration**) is a critical step in the cellular phase of acute inflammation [1]. It refers to the process by which leukocytes (primarily neutrophils) squeeze through the intercellular junctions between endothelial cells to exit the blood vessel and enter the interstitial space [2]. **1. Why Option B is Correct:** After leukocytes undergo rolling and firm adhesion to the vascular endothelium (mediated by selectins and integrins), they migrate through the vessel wall [4]. This process occurs primarily in the **post-capillary venules** [1]. The key molecule facilitating this movement is **PECAM-1 (CD31)**, which is expressed on both the leukocytes and the endothelial cell junctions [2]. Once through the endothelium, the leukocytes secrete collagenases to breach the basement membrane and reach the site of injury [2]. **2. Why the Other Options are Incorrect:** * **Option A:** While leukocytes do pass through the basement membrane, diapedesis specifically encompasses the entire movement through the **vessel wall** (endothelium + basement membrane) [1]. * **Option C:** This describes **platelet aggregation**, a component of primary hemostasis, not inflammation. * **Option D:** This describes **autolysis**, a process of self-destruction seen in cell death or post-mortem changes. **3. High-Yield Clinical Pearls for NEET-PG:** * **Site of Diapedesis:** Post-capillary venules (due to lower flow rates and thinner walls) [1]. * **Key Molecule:** **PECAM-1 (CD31)** is the most important mediator for transmigration [2]. * **Leukocyte Adhesion Deficiency (LAD) Type 1:** Caused by a defect in **CD18 (integrin)**, leading to failed adhesion and diapedesis, clinically presenting as delayed separation of the umbilical cord and recurrent infections without pus formation [2]. * **Sequence of Events:** Margination → Rolling → Adhesion → **Diapedesis** → Chemotaxis [3]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 188-189. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 87-89. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Migration in the tissues toward a chemotactic stimulus, pp. 86-87. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 87.

Question 94: Chronic granulomatous disease is due to deficiency of which enzyme?

A. Opsonization
B. Oxidase (Correct Answer)
C. Lysozyme
D. Cytokines

Explanation: **Explanation:** **Chronic Granulomatous Disease (CGD)** is a primary immunodeficiency caused by a genetic defect in the **NADPH oxidase enzyme complex** (specifically the *gp91phox* subunit in the X-linked form). 1. **Why Oxidase is Correct:** NADPH oxidase is responsible for the **Respiratory Burst**. It converts molecular oxygen into superoxide radicals ($O_2^-$), which are essential for killing phagocytosed microorganisms [1]. In CGD, the absence of this enzyme prevents the formation of reactive oxygen species (ROS) [1]. Consequently, phagocytes can ingest but cannot kill certain bacteria, leading to persistent infections and the formation of **granulomas** as the body attempts to wall off the pathogens [2]. 2. **Why Other Options are Incorrect:** * **Opsonization:** This is the process of coating a pathogen with proteins (like C3b or IgG) to enhance phagocytosis; it is not an enzyme [1]. * **Lysozyme:** An enzyme found in secretions (tears, saliva) that attacks bacterial cell walls; its deficiency does not cause CGD. * **Cytokines:** These are signaling proteins (like IL-1 or TNF) that mediate inflammation; while they are involved in the immune response, CGD is specifically a defect in the microbicidal oxidase system. **High-Yield Clinical Pearls for NEET-PG:** * **Inheritance:** Most common is **X-linked recessive**. * **Pathogens:** Patients are highly susceptible to **Catalase-positive organisms** (e.g., *Staphylococcus aureus*, *Aspergillus*, *Nocardia*, *Serratia marcescens*). * **Diagnostic Tests:** 1. **Nitroblue Tetrazolium (NBT) test:** Cells fail to turn blue (remains colorless/yellow). 2. **Dihydrorhodamine (DHR) flow cytometry:** (Gold Standard) Shows decreased fluorescence. * **Histology:** Characterized by granulomas in skin, liver, and lymph nodes [2]. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 89-91. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 198-200.

Question 95: In acute inflammation, excessive fluid seepage occurs due to increased permeability of?

A. Venules (Correct Answer)
B. Capillaries
C. Arterioles
D. Arterioles and capillaries

Explanation: In acute inflammation, the hallmark of increased vascular permeability is the formation of endothelial gaps [1]. This process is primarily mediated by chemical mediators like histamine, bradykinin, and leukotrienes [3, 4]. **Why Venules are the Correct Answer:** The primary site of increased vascular permeability in acute inflammation is the **post-capillary venules** [1]. This occurs because the density of receptors for inflammatory mediators (such as Histamine H1 receptors) is highest on the endothelial cells of venules compared to other vessel types. When these mediators bind, they cause endothelial cell contraction, leading to the formation of intercellular gaps (0.5–1.0 µm) through which protein-rich fluid (exudate) seeps into the extravascular space [1, 5]. **Explanation of Incorrect Options:** * **Arterioles (C):** While arterioles undergo **vasodilation** (mediated by Nitric Oxide and Prostaglandins) to increase blood flow (rubor and calor), they are generally resistant to the gap-forming effects of primary inflammatory mediators [4]. * **Capillaries (B):** Although capillaries can be involved in cases of direct endothelial injury (e.g., severe burns or toxins), they are not the primary or initial site for mediator-induced leakage [1]. * **Arterioles and Capillaries (D):** This is incorrect as it overlooks the specific physiological role of the post-capillary venules in the inflammatory response [1]. **NEET-PG High-Yield Pearls:** * **Immediate Transient Response:** This is the most common pattern of increased permeability, occurs only in venules, and lasts for 15–30 minutes (mediated by histamine) [1]. * **Immediate Sustained Response:** Occurs in all levels of microcirculation (arterioles, capillaries, venules) due to **direct endothelial cell injury** (e.g., severe burns). * **Delayed Prolonged Leakage:** Involves capillaries and venules (e.g., sunburns), appearing 2–12 hours after injury. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 187-188. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, p. 101. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 93-94. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 84-85.

Question 96: Acute bacterial pyogenic infection manifests as:

A. Leukopenia
B. Leukocytosis (Correct Answer)
C. Neutropenia
D. Lymphopenia

Explanation: **Explanation:** **1. Why Leukocytosis is Correct:** Acute bacterial pyogenic infections trigger a systemic inflammatory response. The body responds by increasing the production and release of white blood cells (WBCs) from the bone marrow into the peripheral blood to combat the invading pathogens [1]. This increase in total WBC count (typically >11,000/mm³) is termed **Leukocytosis**. Specifically, pyogenic (pus-forming) bacteria like *Staphylococcus aureus* or *Streptococcus pneumoniae* induce a **Neutrophilic Leukocytosis**, often accompanied by a "left shift" (increased immature forms like band cells) [1], [2]. **2. Why the Other Options are Incorrect:** * **Leukopenia (A) & Neutropenia (C):** These refer to a decrease in total WBCs or neutrophils, respectively. While severe overwhelming sepsis or specific infections (like Typhoid or certain viral infections) can cause leukopenia, it is not the standard manifestation of an acute pyogenic process. * **Lymphopenia (D):** This is a decrease in lymphocytes. While relative lymphopenia may occur during acute inflammation (as neutrophils dominate the differential count), it is not the primary diagnostic hallmark of a bacterial infection. Lymphocytosis is more characteristic of viral infections (e.g., EBV) [2]. **3. NEET-PG High-Yield Pearls:** * **Left Shift:** The presence of immature neutrophils (band cells, metamyelocytes) in the blood during acute infection is known as "shift to the left." * **Leukemoid Reaction:** An extreme elevation of WBC count (>50,000/mm³) mimicking leukemia, often seen in severe pyogenic infections (e.g., perforated appendicitis). * **Toxic Granulations:** Look for dark, coarse granules in the cytoplasm of neutrophils on a peripheral smear; these are a classic sign of severe bacterial infection. * **Döhle Bodies:** Small, blue, peripheral cytoplasmic inclusions in neutrophils, often seen alongside leukocytosis in inflammatory states. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Diseases of White Blood Cells, Lymph Nodes, Spleen, and Thymus, p. 592. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Blood And Bone Marrow Disease, pp. 580-581.

Question 97: Laminin and fibronectin are involved in which of the following cell functions?

A. Adhesion
B. Migration
C. Apoptosis (Correct Answer)
D. Differentiation

Explanation: ### Explanation The correct answer is **C. Apoptosis**. While laminin and fibronectin are traditionally associated with structural support, they play a critical role in cell survival through a process known as **anoikis**. Anoikis is a form of programmed cell death (apoptosis) induced by the loss of cell-matrix interactions [1]. When cells lose their attachment to the extracellular matrix (ECM) proteins like **laminin** and **fibronectin**, survival signals (mediated via integrins) are terminated, triggering the intrinsic apoptotic pathway [1], [2]. This mechanism ensures that cells do not survive or proliferate in inappropriate locations, preventing metastatic spread. #### Analysis of Options: * **A. Adhesion:** While laminin and fibronectin are primary mediators of cell adhesion [2], the question specifically tests their regulatory role in cell fate. In the context of pathology and cell survival, their *absence* or *detachment* is a classic trigger for apoptosis. * **B. Migration:** Fibronectin acts as a "pathway" for migrating cells (e.g., during wound healing), but this is a secondary function compared to its role in maintaining cell viability [2]. * **D. Differentiation:** Though the ECM influences stem cell differentiation [2], it is not the primary physiological function associated with these specific glycoproteins in standard pathology curricula. #### NEET-PG High-Yield Pearls: * **Fibronectin:** A high-molecular-weight glycoprotein that binds to **integrins** [2]. It is crucial in "plasma" form for blood clotting and in "tissue" form for wound healing (forming the provisional matrix). * **Laminin:** The most abundant glycoprotein in the **basal lamina**. It connects cells to Type IV collagen. * **Anoikis:** A specific subtype of apoptosis. Resistance to anoikis is a hallmark of **malignant transformation** and epithelial-mesenchymal transition (EMT). * **RGD Sequence:** Fibronectin binds to integrins via the **Arg-Gly-Asp (RGD)** tripeptide motif [2]—a frequent examiner favorite. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 80-81. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 36-37.

Question 98: What is a sign of chronic inflammation?

A. Angiogenesis (Correct Answer)
B. Purulent exudate
C. Induration
D. Edema

Explanation: **Explanation:** Chronic inflammation is a prolonged process (weeks to months) where inflammation, tissue injury, and attempts at repair coexist [1]. The hallmark of chronic inflammation is the replacement of damaged tissue with connective tissue, a process involving **Angiogenesis** (the formation of new blood vessels) and fibrosis [1]. **Why Angiogenesis is correct:** During chronic inflammation, macrophages and lymphocytes release growth factors like **VEGF** (Vascular Endothelial Growth Factor) and **FGF-2**. These stimulate the proliferation of new capillaries to supply nutrients and oxygen to the developing granulation tissue, facilitating the repair process [1]. **Analysis of Incorrect Options:** * **Purulent exudate (B):** This is a characteristic of **acute inflammation**, specifically "suppurative inflammation," typically caused by pyogenic bacteria (e.g., Staphylococci). It consists of neutrophils, liquefied debris, and edema fluid. * **Edema (D):** This is one of the cardinal signs of **acute inflammation** (*Tumor*), resulting from increased vascular permeability and fluid leakage into the interstitial space [1]. * **Induration (C):** While often associated with chronic processes (like a positive Mantoux test), induration refers to the hardening of tissue. In the context of the classic morphological features of inflammation, angiogenesis is the more definitive pathological hallmark of the chronic proliferative phase. **High-Yield NEET-PG Pearls:** * **Cellular Hallmark:** The predominant cells in chronic inflammation are **Macrophages**, Lymphocytes, and Plasma cells (Mononuclear cells) [2]. * **Granulomatous Inflammation:** A specific subtype of chronic inflammation characterized by epithelioid histiocytes (activated macrophages) [2]. * **Key Cytokines:** TNF-α and IL-1 drive acute responses; **IFN-γ** (from Th1 cells) is the primary activator of macrophages in chronic inflammation. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 103-119. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 194-197.

Question 99: A scientist is working in the laboratory on the mechanisms involved in inflammation. He observes that leucocytes leave the blood vessels and move towards the site of bacteria. Which of the following is likely to mediate this movement of leucocytes?

A. C3a
B. C5a (Correct Answer)
C. Histamine
D. C3b

Explanation: The process described in the question is **Chemotaxis**, which is the unidirectional movement of leukocytes toward a chemical gradient at the site of injury or infection [3], [4]. **Why C5a is Correct:** C5a is a potent **chemotactic factor** and an anaphylatoxin [1]. It is a product of the complement cascade (classical, alternative, or lectin pathways). It acts by binding to specific G-protein coupled receptors on the surface of leukocytes (neutrophils, monocytes), triggering the polymerization of actin and the formation of filopodia, which allows the cell to "crawl" toward the source of the stimulus. **Analysis of Incorrect Options:** * **C3a:** While C3a is an **anaphylatoxin** (increases vascular permeability by triggering histamine release from mast cells), it has negligible chemotactic activity compared to C5a [2]. * **Histamine:** This is a primary mediator of **vasodilation** and increased vascular permeability (causing "gaps" in the endothelium) [2]. It acts during the early phase of inflammation but does not direct the movement of cells toward bacteria. * **C3b:** This molecule acts as an **opsonin** [3]. It coats the surface of bacteria to facilitate recognition and engulfment by phagocytes (phagocytosis) but does not mediate the movement of cells to the site [1], [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Major Chemotactic Agents:** Remember the mnemonic **"C-I-L-B"**: **C**5a, **I**L-8, **L**eukotriene **B**4 (LTB4), and **B**acterial products (N-formyl methionine). * **Exogenous vs. Endogenous:** Bacterial products are exogenous chemoattractants; C5a, LTB4, and IL-8 are endogenous. * **Phagocytosis:** C3b and IgG are the two most important opsonins [3]. * **Adhesion:** Selectins mediate "rolling," while Integrins (activated by chemokines) mediate "firm adhesion" [5]. **References:** [1] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 163-164. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 99-100. [3] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. (Basic Pathology) introduces the student to key general principles of pathology, both as a medical science and as a clinical activity with a vital role in patient care. Part 2 (Disease Mechanisms) provides fundamental knowledge about the cellular and molecular processes involved in diseases, providing the rationale for their treatment. Part 3 (Systematic Pathology) deals in detail with specific diseases, with emphasis on the clinically important aspects., pp. 190-191. [4] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Inflammation and Repair, pp. 87-89. [5] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. Migration in the tissues toward a chemotactic stimulus, pp. 86-87.

Question 100: Which of the following exhibits both morphogenic and mitogenic properties?

A. Fibroblast growth factor
B. Platelet derived growth factor
C. Bone morphogenetic protein (Correct Answer)
D. Insulin-like growth factor

Explanation: **Explanation:** The correct answer is **Bone Morphogenetic Protein (BMP)**. BMPs are members of the **Transforming Growth Factor-̠ (TGF-̠) superfamily** [1]. They are unique because they possess dual properties: 1. **Mitogenic:** They stimulate the proliferation (mitosis) of mesenchymal stem cells and osteoblasts [1]. 2. **Morphogenic:** They induce the differentiation of non-osseous mesenchymal cells into osteoblasts and chondrocytes, effectively "shaping" the formation of bone and cartilage [1]. This ability to direct tissue architecture makes them true morphogens. **Analysis of Incorrect Options:** * **A. Fibroblast Growth Factor (FGF):** Primarily a potent mitogen for mesenchymal cells and a key mediator of angiogenesis. While it influences development, it is not classified as a classic morphogen in the context of bone induction like BMP. * **B. Platelet-Derived Growth Factor (PDGF):** A strong chemoattractant and mitogen for fibroblasts, smooth muscle cells, and macrophages [2]. It is vital for wound healing and granulation tissue formation but lacks primary morphogenic patterning properties [2]. * **D. Insulin-like Growth Factor (IGF-1):** Acts mainly as a mitogen that promotes cell survival and growth (hypertrophy/hyperplasia) in response to Growth Hormone, but it does not induce de novo tissue morphogenesis. **High-Yield Clinical Pearls for NEET-PG:** * **BMP-2 and BMP-7** (Osteogenic Protein-1) are used clinically in orthopedic surgery to treat non-union fractures. * **TGF-̠** is the most important cytokine for synthesis and deposition of connective tissue proteins (fibrosis). * Remember: **Morphogens** create a concentration gradient that specifies cell fate during embryonic development and tissue repair. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Lung, pp. 706-707. [2] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. With Illustrations By, pp. 31-32.

Practice by Chapter

Acute Inflammation: Vascular Events

Practice Questions

Acute Inflammation: Cellular Events

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Chemical Mediators of Inflammation

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Chronic Inflammation

Practice Questions

Granulomatous Inflammation

Practice Questions

Systemic Effects of Inflammation

Practice Questions

Wound Healing

Practice Questions

Tissue Regeneration

Practice Questions

Fibrosis and Repair

Practice Questions

Resolution of Inflammation

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