Microscopic Anatomy Practice Questions

Q: What are the supporting cells of the testes?

Sertoli cells. **Explanation:** The correct answer is **C. Sertoli cells**. Sertoli cells are the large, columnar "nurse cells" located within the germinal epithelium of the seminiferous tubules [1]. They are considered the **supporting cells** of the testes because they provide structural integrity, nutrition, and protection to developing germ cells [1], [2]. They are also responsible for forming the **blood-testis barrier** via tight junctions, protecting sperm from the immune system [1]. **Analysis of Options:** * **Spermatogonia (A):** These are the undifferentiated male germ cells (stem cells) located on the basement membrane [1]. They are the precursors to sperm, not supporting cells. * **Leydig cells (B):** Also known as interstitial cells, these are found in the connective tissue *between* seminiferous tubules. Their primary function is the endocrine production of **Testosterone** in response to LH [3]. * **Spermatids (D):** These are haploid male germ cells derived from secondary spermatocytes. They represent a late stage of spermatogenesis before undergoing spermiogenesis to become mature spermatozoa [2]. **High-Yield Facts for NEET-PG:** * **Secretions:** Sertoli cells secrete **Inhibin B** (inhibits FSH), **Androgen Binding Protein (ABP)** (maintains high local testosterone), and **Anti-Müllerian Hormone (AMH)** during fetal development [2], [3]. * **Regulation:** Sertoli cells are stimulated by **FSH**, whereas Leydig cells are stimulated by **LH** (Mnemonic: **L**H acts on **L**eydig cells) [3]. * **Phagocytosis:** Sertoli cells phagocytose the excess cytoplasm (residual bodies) shed by spermatids during spermiogenesis. * **Tumor Marker:** Sertoli cells contain **Charcot-Böttcher crystals** (spindle-shaped cytoplasmic inclusions), which are pathognomonic.

Q: Which type of cells are not found in the stomach?

Goblet cells. **Explanation:** The correct answer is **Goblet cells**. The gastric mucosa is lined by a simple columnar epithelium that forms "surface mucous cells," which secrete a protective layer of alkaline mucus. However, true **Goblet cells** (unicellular glands characterized by a constricted base and a distended apical end filled with mucin) are characteristic of the **small and large intestines**, not the stomach. **Analysis of Options:** * **Chief Cells (Peptic/Zymogenic cells):** Found primarily in the base of the gastric glands (body and fundus) [2]. They secrete pepsinogen and gastric lipase [3]. * **Parietal Cells (Oxyntic cells):** Located mainly in the neck and body of gastric glands [2]. They secrete Hydrochloric acid (HCl) and Intrinsic Factor of Castle [3]. * **Argentaffin Cells (Enterochromaffin cells):** These are a type of Enteroendocrine cell found throughout the gastrointestinal tract, including the stomach [1]. They secrete serotonin and histamine to regulate gastric motility and secretion [1]. **High-Yield NEET-PG Pearls:** 1. **Intestinal Metaplasia:** The presence of Goblet cells in the gastric mucosa is a pathological finding (often due to chronic *H. pylori* gastritis) and is considered a pre-cancerous lesion. 2. **Parietal Cell Histology:** They are characterized by an abundance of mitochondria and an intracellular canalicular system [3]. They are stained intensely eosinophilic (pink) on H&E stain. 3. **Vitamin B12:** Destruction of parietal cells (as seen in Atrophic Gastritis) leads to a deficiency of Intrinsic Factor, resulting in **Pernicious Anemia**.

Q: Sinusoids are seen in all of the following organs except?

Kidney. ### Explanation **Conceptual Overview** Sinusoids are a specialized type of **discontinuous capillary** characterized by a wide, irregular lumen, a fenestrated endothelium with large gaps, and a partial or absent basement membrane [1]. These features allow for the free exchange of large molecules (like proteins) and even whole cells between the blood and the surrounding tissue [2]. **Why Kidney is the Correct Answer** The kidney contains **fenestrated capillaries** (specifically in the glomerulus and peritubular network), but it does **not** contain sinusoids [1]. Unlike sinusoids, fenestrated capillaries in the kidney have a **thick, continuous basement membrane** that acts as a critical filtration barrier to prevent the passage of large proteins and blood cells into the primary urine [1]. **Analysis of Incorrect Options** * **Liver (A):** The liver is the classic example of sinusoidal architecture [2]. Hepatic sinusoids allow plasma to come into direct contact with hepatocytes in the Space of Disse for metabolic processing [3]. * **Lymph nodes (C):** These contain lymphatic sinusoids (subcapsular, cortical, and medullary) which facilitate the slow flow of lymph, allowing macrophages to filter antigens. * **Spleen (D):** The red pulp of the spleen contains splenic sinusoids (venous sinusoids). These are essential for "pitting" and "culling" of aged or abnormal red blood cells. **NEET-PG High-Yield Pearls** * **Locations of Sinusoids:** Remember the mnemonic **"LBS"** (Liver, Bone marrow, Spleen) + Adrenal cortex, Anterior Pituitary, and Lymph nodes. * **Basement Membrane:** The defining difference between a fenestrated capillary (Kidney/Endocrine glands) and a sinusoid is the **continuity of the basement membrane** (Continuous in fenestrated; Discontinuous/Absent in sinusoids) [1]. * **Spleen Specifics:** Splenic sinusoids are lined by long, rod-shaped endothelial cells called **Stave cells**.

Q: Which of the following organs does NOT contain sinuses?

Kidney. The correct answer is **Kidney**. In histology, **sinusoids** (or sinuses) are specialized, wide-diameter, thin-walled capillaries with large fenestrations and a discontinuous basement membrane [1]. They allow for the exchange of large molecules and cells between the blood and the surrounding tissue. 1. **Why Kidney is the correct answer:** The kidney contains **fenestrated capillaries** (specifically in the glomerulus and peritubular network), but it does **not** contain sinusoids [1]. The renal "sinus" is an anatomical space containing the renal pelvis and vessels, but it is not a vascular sinusoid. 2. **Why the other options are incorrect:** * **Spleen:** Contains prominent **venous sinusoids** in the red pulp, lined by "stave cells" that filter aged red blood cells. * **Endocrine Glands:** Many endocrine glands (like the pituitary and adrenal glands) contain sinusoids to facilitate the rapid entry of large hormone molecules into the bloodstream [1]. * **Liver:** The liver is the classic example of an organ with **discontinuous sinusoids**, where blood from the portal vein and hepatic artery mixes before reaching the central vein [2], [3]. **High-Yield Clinical Pearls for NEET-PG:** * **Locations of Sinusoids:** Remember the mnemonic **"L-B-S-E"** (Liver, Bone marrow, Spleen, Endocrine glands) [4]. * **Liver Sinusoids:** Contain **Kupffer cells** (fixed macrophages) and are separated from hepatocytes by the **Space of Disse** [2]. * **Spleen:** The splenic sinusoids act as a "mechanical filter"; RBCs must be flexible to squeeze through the stave cell gaps. * **Capillary Types:** * *Continuous:* Muscle, Lung, CNS (Blood-Brain Barrier). * *Fenestrated:* Kidney (Glomerulus), Intestine, Endocrine glands [1]. * *Sinusoidal:* Liver, Spleen, Bone Marrow [4].

Q: All of the following statements are true except?

Stellate cells are modified macrophages in the liver.. ### **Explanation** The question asks to identify the incorrect statement regarding the **Mononuclear Phagocyte System (MPS)**. **1. Why Option C is the Correct (Incorrect) Statement:** In the liver, the resident macrophages are **Kupffer cells**, which are located within the hepatic sinusoids [3]. **Stellate cells** (also known as Ito cells), located in the space of Disse [1], are not macrophages; they are specialized cells responsible for **Vitamin A storage**. In pathological states (like chronic alcohol use), they transform into myofibroblasts and produce collagen, leading to liver fibrosis and cirrhosis. **2. Analysis of Other Options:** * **Option A:** **Microglial cells** are the resident macrophages of the Central Nervous System (CNS) [3]. They are unique because they are derived from the yolk sac (mesoderm), unlike other brain cells which are ectodermal. * **Option B:** **Hofbauer cells** are mesenchymal macrophages found in the chorionic villi of the placenta. They play a role in preventing vertical transmission of pathogens. * **Option C:** **Osteoclasts** are multinucleated giant cells in the bone derived from the fusion of monocyte-macrophage precursors [3]. They are responsible for bone resorption [2], [4]. **3. NEET-PG High-Yield Pearls:** * **Dust Cells:** Alveolar macrophages in the lungs [3]. * **Langerhans Cells:** Antigen-presenting macrophages in the skin (contain Birbeck granules). * **Mesangial Cells:** Specialized macrophages in the kidney glomerulus. * **Littoral Cells:** Macrophages found in the splenic sinusoids. * **Heart Failure Cells:** Siderophages (hemosiderin-laden macrophages) found in the alveoli during left heart failure.

Q: What is the positive zone of enamel caries?

Dark zone. ### Explanation In the histopathology of enamel caries, the lesion is divided into four distinct zones based on the degree of demineralization and the size of the resulting pores. **Why the Dark Zone is correct:** The **Dark Zone** is referred to as the "positive zone" because it appears dark under a polarizing microscope when mounted in quinoline. This occurs because the zone contains very small "micropores" (2–4% mineral loss) that are too small for the large molecules of quinoline to enter. These pores remain filled with air or vapor, which scatters light, resulting in a dark appearance. It is considered a zone of active remineralization and is a hallmark of a progressing lesion. **Analysis of Incorrect Options:** * **A. Translucent Zone:** This is the advancing front of the lesion. It is called "translucent" because its pores (1% mineral loss) are large enough to be completely filled by quinoline, making it appear clear. * **C. Body of the Lesion:** This is the area of maximum demineralization (5–25% mineral loss). It has the largest pores, which are easily filled by the mounting medium, making it appear relatively clear compared to the dark zone. * **D. Surface Zone:** This is the relatively intact outer layer (1% mineral loss). It remains mineralized due to constant exposure to fluoride and minerals from saliva. **High-Yield NEET-PG Pearls:** * **Order of zones (from deep to superficial):** Translucent zone → Dark zone → Body of the lesion → Surface zone. * **The Dark Zone** is a "dynamic" zone; its presence indicates that remineralization is occurring. * **The Translucent Zone** is the first recognizable histological change in enamel caries. * **Pore Volume:** Translucent (1%) < Dark (2-4%) < Body of lesion (5-25%).

Q: Serous demilunes are present in large numbers in which gland?

Submandibular. The correct answer is **Submandibular gland**. **1. Why Submandibular is Correct:** Salivary glands are classified based on their secretion type: serous, mucous, or mixed. The **submandibular gland** is a **mixed gland** with a predominant serous component. Serous demilunes (also known as **Giannuzzi's crescents**) are characteristic histological features of mixed glands. They consist of cap-like clusters of serous cells situated at the periphery of mucous acini. During traditional histological preparation, the swelling of mucous cells pushes the serous cells outward, creating the "half-moon" or demilune appearance. **2. Analysis of Incorrect Options:** * **Parotid Gland:** This is a **purely serous** gland. Since it lacks mucous acini, it does not contain serous demilunes. * **Sublingual Gland:** This is a mixed gland but is **predominantly mucous**. While it may contain some demilunes, they are significantly more numerous and characteristic in the submandibular gland. * **Pituitary Gland:** This is an endocrine gland composed of cords of epithelial cells (acidophils, basophils, and chromophobes) and does not contain exocrine acini or demilunes. **3. NEET-PG High-Yield Pearls:** * **Secretory Ratio:** Submandibular (80% serous, 20% mucous); Sublingual (predominantly mucous). * **Staining:** Serous cells are protein-secreting (basophilic cytoplasm due to RER); Mucous cells contain mucin (pale/vacuolated appearance). * **Myoepithelial cells:** Located between the basal lamina and acinar cells; they contract to expel secretions into the duct system. * **Ducts:** The submandibular gland has the most prominent **striated ducts**, which are involved in ion reabsorption.

Q: The juxtaglomerular apparatus is located in relation to which renal structure?

Glomerulus. **Explanation:** The **Juxtaglomerular Apparatus (JGA)** is a specialized structure located at the **vascular pole of the renal corpuscle (Glomerulus)** [1]. It serves as a critical regulatory unit that monitors systemic blood pressure and glomerular filtration rate (GFR). The JGA is formed by the anatomical contact between the **afferent arteriole** (and sometimes the efferent arteriole) and the **thick ascending limb/distal convoluted tubule** of the same nephron [1]. Because it is physically situated at the entry and exit point of the glomerular capillaries, it is considered anatomically and functionally related to the **Glomerulus** [4]. **Analysis of Options:** * **Proximal Convoluted Tubule (A):** This is located at the urinary pole of the glomerulus, opposite the JGA [2]. * **Ascending Loop of Henle (B):** While the *thick* ascending limb returns to touch the glomerulus (forming the Macula Densa), the JGA as a complex is defined by its relationship to the glomerular hilum. * **Descending Loop of Henle (C):** This segment is located deep in the medulla and has no physical contact with the vascular pole of the nephron. **NEET-PG High-Yield Pearls:** 1. **Components of JGA:** * **Juxtaglomerular (JG) Cells:** Modified smooth muscle cells of the afferent arteriole; they secrete **Renin** [1][3]. * **Macula Densa:** Specialized columnar cells of the distal tubule; they act as **chemoreceptors** for sodium chloride (NaCl) levels. * **Lacis Cells (Extraglomerular Mesangial Cells):** Located in the triangular space between the arterioles and the macula densa. 2. **Function:** It regulates the **Renin-Angiotensin-Aldosterone System (RAAS)** and mediates **Tubuloglomerular Feedback** [3].

Q: Node of Ranvier is seen in which part of a neuron?

Axons. The **Node of Ranvier** refers to the periodic gaps (approximately 1 μm wide) in the myelin sheath along the length of an **axon**. [1] These gaps are essential for **saltatory conduction**, where the action potential "jumps" from one node to the next, significantly increasing the speed of nerve impulse transmission. [1] * **Why Axon is correct:** Myelination is a specific feature of axons. [1] In the Peripheral Nervous System (PNS), Schwann cells wrap around the axon, while in the Central Nervous System (CNS), oligodendrocytes perform this function. [1] The segments between nodes are called internodes. The nodal membrane is highly enriched with **voltage-gated sodium (Na+) channels**, which are necessary for regenerating the action potential. [1] * **Why other options are incorrect:** * **Cell body (Soma):** Contains the nucleus and organelles (like Nissl bodies) but lacks a myelin sheath; therefore, no nodes are present. [1] * **Dendrites:** These are typically unmyelinated processes that receive signals. [1] * **Terminal buttons:** These are the distal ends of axon branches that form synapses; they are specialized for neurotransmitter release, not impulse propagation via myelin gaps. [1] **High-Yield Clinical Pearls for NEET-PG:** * **Saltatory Conduction:** This mechanism is energy-efficient as it localizes metabolic activity (Na+/K+ ATPase pump) primarily to the nodes. * **Demyelinating Diseases:** In **Multiple Sclerosis** (CNS) and **Guillain-Barré Syndrome** (PNS), the myelin sheath is damaged, disrupting conduction at these nodes and leading to neurological deficits. [1] * **Caspr Protein:** A specific molecular marker found in the paranodal regions adjacent to the Node of Ranvier.

Question 1

What are the supporting cells of the testes?

Accepted Answer

Sertoli cells

Answer

Spermatogonia

Answer

Leydig cells

Answer

Spermatids

Question 2

Which type of cells are not found in the stomach?

Accepted Answer

Goblet cells

Answer

Chief cells

Answer

Parietal cells

Answer

Argentaffin cells

Question 3

Sinusoids are seen in all of the following organs except?

Accepted Answer

Kidney

Answer

Liver

Answer

Lymph nodes

Answer

Spleen

Question 4

Which of the following is NOT true about terminal bronchioles?

Accepted Answer

Absence of smooth muscles

Answer

Absence of cartilage

Answer

Presence of Clara cells

Answer

Absence of submucous glands

Question 5

Which of the following organs does NOT contain sinuses?

Accepted Answer

Kidney

Answer

Spleen

Answer

Endocrine gland

Answer

Liver

Question 6

All of the following statements are true except?

Accepted Answer

Stellate cells are modified macrophages in the liver.

Answer

Microglial cells are modified macrophages in the brain.

Answer

Hofbauer cells are modified macrophages in the placenta.

Answer

Osteoclasts are modified macrophages.

Question 7

What is the positive zone of enamel caries?

Accepted Answer

Dark zone

Answer

Translucent zone

Answer

Body of the lesion

Answer

Surface zone

Question 8

Serous demilunes are present in large numbers in which gland?

Accepted Answer

Submandibular

Answer

Parotid

Answer

Sublingual

Answer

Pituitary

Question 9

The juxtaglomerular apparatus is located in relation to which renal structure?

Accepted Answer

Glomerulus

Answer

Proximal convoluted tubule

Answer

Ascending loop of Henle

Answer

Descending loop of Henle

Question 10

Node of Ranvier is seen in which part of a neuron?

Accepted Answer

Axons

Answer

Cell body

Answer

Dendrites

Answer

Terminal buttons

Microscopic Anatomy — MCQs

Microscopic Anatomy — MCQs

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