Histology Practice Questions

Q: Which cells in the gastrointestinal tract sample antigens to Peyer's patches?

Microfold cells. ### Explanation **Correct Answer: A. Microfold cells (M cells)** **Mechanism:** Microfold cells (M cells) are specialized epithelial cells located within the **Follicle-Associated Epithelium (FAE)** that overlies Peyer’s patches in the ileum [2]. Unlike typical enterocytes, M cells lack a well-developed brush border (microvilli) and a thick glycocalyx. Their primary function is **transcytosis**: they sample luminal antigens, bacteria, and viruses, transporting them across the epithelial barrier to underlying dendritic cells and lymphocytes within the Peyer’s patch [2]. This initiates the mucosal immune response. **Analysis of Incorrect Options:** * **B. G cells:** These are enteroendocrine cells located primarily in the antrum of the stomach. They secrete **gastrin**, which stimulates gastric acid secretion, but they do not have an immune-sampling role [1]. * **C. Langerhans cells:** These are dendritic (antigen-presenting) cells found in the **stratum spinosum of the epidermis** and squamous epithelium (e.g., esophagus). While they sample antigens, they are not the primary cells associated with Peyer's patches in the intestinal mucosa. * **D. T cells:** These are effector lymphocytes of the adaptive immune system. While T cells are found *within* Peyer’s patches to receive presented antigens, they do not perform the initial sampling/transport from the intestinal lumen [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Pathogen Entry:** Certain pathogens exploit M cells as a portal of entry into the body, most notably ***Salmonella typhi***, *Shigella*, and Poliovirus [2]. * **Histology:** M cells are characterized by a "pocket" on their basolateral surface which houses B-lymphocytes, T-lymphocytes, and macrophages. * **Peyer’s Patches:** These are macroscopic lymphoid aggregates found predominantly in the **lamina propria and submucosa of the ileum** [1]. They are a key component of GALT (Gut-Associated Lymphoid Tissue).

Q: Anemia which is associated with pancytopenia is?

Megaloblastic. **Explanation:** **Megaloblastic Anemia** is the correct answer because it is characterized by a defect in **DNA synthesis**, most commonly due to Vitamin B12 or Folic acid deficiency [1]. This defect does not just affect red blood cells; it affects all rapidly dividing cells in the bone marrow. When DNA synthesis is impaired, the maturation of the nucleus lags behind the cytoplasm (**nuclear-cytoplasmic asynchrony**), leading to ineffective hematopoiesis. This results in the premature destruction of precursors within the marrow (intramedullary hemolysis), leading to a reduction in all three cell lines: anemia (RBCs), leukopenia (WBCs), and thrombocytopenia (platelets)—a condition known as **pancytopenia**. **Why other options are incorrect:** * **Hemolytic Anemia:** This involves the premature destruction of mature red blood cells in the peripheral circulation or spleen. While RBC counts drop, the bone marrow is typically hyperactive and compensates by increasing the production of WBCs and platelets. * **Iron Deficiency Anemia:** This is a defect in **hemoglobin synthesis** (heme part), not DNA synthesis. It specifically affects the erythroid lineage, leading to microcytic hypochromic anemia. Platelet counts are often normal or even elevated (reactive thrombocytosis). **NEET-PG High-Yield Pearls:** * **Peripheral Smear:** Look for **hypersegmented neutrophils** (early sign) [1] and macro-ovalocytes. * **Bone Marrow:** Shows "megaloblastic" changes with open, lacy chromatin [1]. * **Pancytopenia Differential:** Always consider Aplastic Anemia (hypocellular marrow) vs. Megaloblastic Anemia (hypercellular marrow). * **MCV:** Typically >100 fL in megaloblastic anemia.

Q: Halocrine secretion is characteristic of which type of gland?

Sebaceous gland. ### Explanation Glands are classified based on their **mode of secretion** (how the secretory product is released from the cell). **1. Why Sebaceous Gland is Correct:** **Holocrine secretion** (derived from the Greek *holos*, meaning "whole") occurs when the entire secretory cell matures, dies, and ruptures to release its contents. The **Sebaceous gland** is the classic example; the oily secretion (sebum) consists of the disintegrated remains of the glandular cells themselves. These cells are continuously replaced by rapid mitotic division of basal cells. **2. Analysis of Incorrect Options:** * **Salivary Glands (Merocrine):** These glands use exocytosis. The secretory vesicles fuse with the plasma membrane and release their contents without any loss of cellular cytoplasm or membrane. Most sweat glands and the pancreas also follow this mode. * **Mammary Glands (Apocrine):** In apocrine secretion, the apical portion of the cell cytoplasm is pinched off along with the secretory product. * **Gastric Glands (Merocrine):** Cells like Chief cells (pepsinogen) and Parietal cells (HCl) release their secretions via exocytosis (merocrine) without cell destruction. **3. High-Yield Clinical Pearls for NEET-PG:** * **Mnemonic for Holocrine:** "**H**olocrine = **H**ole" (The whole cell is lost). * **Mnemonic for Apocrine:** "**A**pocrine = **A**pical" (Only the apex is lost). * **Clinical Correlation:** Acne vulgaris is a disorder of the pilosebaceous unit where holocrine debris and sebum become trapped, leading to inflammation. * **Meibomian Glands:** These are modified sebaceous glands in the tarsal plate of the eye and are also **holocrine**.

Q: All of the following are components of the white pulp of the spleen, except?

Vascular sinus. The spleen is divided into two distinct functional regions: the **White Pulp** (immune function) and the **Red Pulp** (blood filtration) [1]. ### Why "Vascular Sinus" is the Correct Answer **Vascular sinuses** (or splenic sinusoids) are the hallmark of the **Red Pulp**. They are wide, thin-walled blood vessels lined by specialized "stave cells." Their primary role is to filter aged or damaged red blood cells from the circulation [1]. Since they are structural components of the red pulp, they are not found within the white pulp. ### Explanation of Incorrect Options (Components of White Pulp) The white pulp is organized around the **Central Artery** and consists of: * **A. Periarteriolar Lymphoid Sheath (PALS):** A cylindrical collection of lymphocytes surrounding the central artery. It is primarily composed of **T-lymphocytes**. * **B & C. Lymphatic Follicles and B-lymphocytes:** At intervals, the PALS expands to form lymphoid follicles (Malpighian corpuscles). These follicles are rich in **B-lymphocytes** and may contain germinal centers for antibody production. ### NEET-PG High-Yield Pearls * **Marginal Zone:** The boundary between red and white pulp. It is the site where antigen-presenting cells (macrophages and dendritic cells) capture blood-borne antigens. * **Open vs. Closed Circulation:** Humans primarily have "open circulation" where blood from penicillar arterioles empties into the splenic cords before entering the sinuses. * **Stave Cells:** The endothelial cells lining the vascular sinuses. They have slit-like gaps that act as a physical filter for RBCs (testing their deformability) [1]. * **PALS = T-cells; Follicles = B-cells.** (Memory aid: **P**ALS has **T**'s).

Q: What is the most abundant fibrillary collagen found in the basement membrane?

Type 4. The correct answer is **Type 4 Collagen**. The basement membrane is a specialized form of extracellular matrix that underlies all epithelia and surrounds muscle cells and peripheral nerves [1]. Unlike fibrillar collagens that form long, rope-like structures, **Type 4 Collagen** is a **network-forming (non-fibrillar) collagen**. It forms a multi-layered, scaffold-like meshwork that provides structural support and acts as a selective filtration barrier. It is the primary structural component of the *lamina densa* within the basal lamina. **Analysis of Incorrect Options:** * **Type 1:** The most abundant collagen in the human body [2]. It forms thick fibers and is found in high-tension areas like **bone, skin, tendons, and late scars**. * **Type 2:** Primarily found in **cartilage** (hyaline and elastic) and the vitreous humor. It provides resistance to pressure. * **Type 3 (Reticulin):** Forms thin, branching fibers that create a supportive framework for highly cellular organs like the **liver, spleen, and lymph nodes**. It is also prominent in early wound healing (granulation tissue). **High-Yield Clinical Pearls for NEET-PG:** * **Goodpasture Syndrome:** Autoantibodies are directed against the alpha-3 chain of Type 4 Collagen, leading to glomerulonephritis and pulmonary hemorrhage. * **Alport Syndrome:** A genetic defect in Type 4 Collagen synthesis resulting in hereditary nephritis, sensorineural deafness, and ocular defects ("Can't see, can't pee, can't hear high C"). * **Mnemonic for Collagen Types:** * Type **1**: **B**one (and Skin) * Type **2**: **C**artilage * Type **3**: **R**eticular fibers * Type **4**: **F**loor (Basement membrane)

Q: Hyaline cartilage is located at all sites except?

Menisci of Knee joint. ### Explanation The correct answer is **B. Menisci of Knee joint**. **1. Why Menisci of Knee joint is correct:** The menisci of the knee joint are composed of **Fibrocartilage**, not hyaline cartilage. Fibrocartilage is characterized by dense bundles of Type I collagen fibers, providing high tensile strength and shock absorption. It lacks a perichondrium and is found in areas subject to heavy pressure and stretch, such as the intervertebral discs, pubic symphysis, and intra-articular discs (menisci). **2. Why the other options are incorrect:** * **Costal cartilage (A):** These connect the ribs to the sternum and are classic examples of hyaline cartilage. * **Articular cartilage (C):** The smooth, glass-like surface covering the ends of bones in synovial joints is hyaline cartilage [1]. Note: It is unique because it lacks a perichondrium. * **Epiphyseal plate (D):** Also known as the growth plate, it consists of hyaline cartilage and is responsible for the longitudinal growth of long bones via endochondral ossification [2]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hyaline Cartilage:** Most common type; contains **Type II collagen** [1]. Locations include the nose, larynx (thyroid, cricoid), trachea, bronchi, and fetal skeleton [2]. * **Elastic Cartilage:** Contains Type II collagen + Elastic fibers. Locations (The "E"s): **E**xternal ear, **E**ustachian tube, and **E**piglottis. * **Fibrocartilage:** Contains **Type I collagen**. It is the strongest type of cartilage. * **Regeneration:** Cartilage has limited repair capacity because it is **avascular** (receives nutrients via diffusion) [1].

Q: What is the most common presenting sign of carcinoma of the urinary bladder?

Hematuria. **Explanation:** **Carcinoma of the urinary bladder** (most commonly Urothelial/Transitional Cell Carcinoma) typically presents in older adults, often with a history of smoking or occupational exposure to aniline dyes. **1. Why Hematuria is Correct:** The hallmark clinical presentation of bladder cancer is **painless, gross (macroscopic) hematuria** throughout the urinary stream. This occurs because the neoplastic tissue is highly vascular and friable; as the tumor grows, surface vessels rupture easily, leading to bleeding into the bladder lumen. In NEET-PG, any elderly patient presenting with painless hematuria should be considered to have a malignancy until proven otherwise. **2. Analysis of Incorrect Options:** * **A & C (Dysuria and Frequency):** These are symptoms of bladder irritation (cystitis). While they can occur if the tumor is large, necrotic, or associated with an infection, they are secondary symptoms and far less common as the *initial* presenting sign compared to hematuria. * **D (Abdominal Lump):** A palpable mass is a late-stage finding indicating advanced, muscle-invasive disease or regional spread. It is rarely the presenting sign in early-stage carcinoma. **3. NEET-PG High-Yield Pearls:** * **Gold Standard Investigation:** Cystoscopy with biopsy is the definitive diagnostic tool. * **Most Common Type:** Transitional Cell Carcinoma (TCC) / Urothelial Carcinoma (>90%). * **Risk Factors:** Smoking (most common), exposure to 2-Naphthylamine (aniline dyes), and *Schistosoma haematobium* (specifically associated with **Squamous Cell Carcinoma**). * **Classic Triad:** Painless hematuria, frequency, and dysuria (though hematuria remains the most common).

Question 1

Which cells in the gastrointestinal tract sample antigens to Peyer's patches?

Accepted Answer

Microfold cells

Answer

G cells

Answer

Langerhans cells

Answer

T cells

Question 2

Which one of the following statements concerning Loose Connective Tissue is true?

Accepted Answer

It acts as a medium for exchange of nutrients and wastes between the blood and tissues.

Answer

It is less abundant than Dense Connective Tissue.

Answer

It has a lower proportion of cells to fibers than does Dense Connective Tissue.

Answer

It provides structural support for organs.

Question 3

Which one of the following statements concerning liver sinusoids is true?

Accepted Answer

The space of Disse is located between sinusoidal cells and hepatocytes.

Answer

Their lining includes Ito cells.

Answer

They receive bile from the hepatocytes.

Answer

They are lined by fenestrated endothelial cells.

Question 4

Anemia which is associated with pancytopenia is?

Accepted Answer

Megaloblastic

Answer

Hemolytic

Answer

Iron deficiency

Answer

All

Question 5

Halocrine secretion is characteristic of which type of gland?

Accepted Answer

Sebaceous gland

Answer

Salivary gland

Answer

Mammary gland

Answer

Gastric gland

Question 6

All of the following are components of the white pulp of the spleen, except?

Accepted Answer

Vascular sinus

Answer

Periaeriolar lymphoid sheath

Answer

Lymphatic follicle

Answer

B lymphocytes

Question 7

What is the most abundant fibrillary collagen found in the basement membrane?

Accepted Answer

Type 4

Answer

Type 1

Answer

Type 2

Answer

Type 3

Question 8

Hyaline cartilage is located at all sites except?

Accepted Answer

Menisci of Knee joint

Answer

Costal cartilage

Answer

Articular cartilage

Answer

Epiphyseal plate

Question 9

What is the most common presenting sign of carcinoma of the urinary bladder?

Accepted Answer

Hematuria

Answer

Dysuria

Answer

Frequency

Answer

Abdominal lump

Question 10

From which structure are fibroblasts derived?

Accepted Answer

Local mesenchyme

Answer

Macrophage

Answer

Endothelium

Answer

Vessels

Histology — MCQs

Histology — MCQs

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