Histology Practice Questions

Q: Fenestrations are seen in which vascular layer?

Endothelium. Explanation: 1. Why Endothelium is Correct: Fenestrations are specialized circular "pores" or openings found within the endothelial cells (tunica intima) of specific capillaries [1]. These pores are approximately 60–80 nm in diameter and are often bridged by a thin diaphragm [1]. Their primary function is to allow the rapid exchange of water and solutes between the blood and tissues [2]. Fenestrated capillaries are typically found in organs requiring high filtration or absorption rates, such as the renal glomeruli, endocrine glands, and intestinal mucosa [1]. 2. Why Other Options are Incorrect: * Internal Elastic Lamina (IEL): This is a layer of elastic tissue that separates the tunica intima from the tunica media. While it contains "fenestrae" (openings) to allow nutrients to diffuse to the deeper layers of the vessel wall, in the context of standard histology and vascular permeability, "fenestrations" specifically refer to the endothelial pores. * External Elastic Lamina (EEL): This layer separates the tunica media from the tunica adventitia. Like the IEL, it is a structural barrier, not a site for physiological capillary exchange. * Tunica Media: This layer consists primarily of smooth muscle cells and elastic fibers. It is responsible for vasoconstriction and vasodilation, not filtration through fenestrations. 3. High-Yield Clinical Pearls for NEET-PG: * Types of Capillaries: * Continuous: Most common (Muscle, Lung, CNS - Blood-Brain Barrier). * Fenestrated: High filtration (Kidney, Small Intestine) [1]. * Sinusoidal/Discontinuous: Largest gaps; allows passage of cells (Liver, Spleen, Bone Marrow) [4]. * Glomerular Filtration Barrier: In the kidney, the fenestrated endothelium is the first line of the filtration barrier, though it prevents the passage of blood cells, it allows most plasma proteins through (the basement membrane and podocytes provide the final size/charge selectivity) [3].

Q: Stave cells are seen in which organ?

Spleen. Stave cells are specialized, elongated endothelial cells that line the **venous sinusoids of the spleen**. They are oriented longitudinally, resembling the wooden staves of a barrel [1]. These cells are held together by transverse reticular fibers, creating a "slat-like" filter. The primary function of stave cells is to act as a physical filter for blood. As blood passes from the splenic cords into the sinusoids, red blood cells (RBCs) must deform to squeeze through the narrow slits between these stave cells [1]. Healthy, flexible RBCs pass through easily, while aged, rigid, or parasitized RBCs (e.g., in malaria or spherocytosis) are trapped and subsequently destroyed by splenic macrophages [1]. **Incorrect Options:** * **A. Liver:** The liver contains **Kupffer cells** (macrophages) and sinusoidal endothelial cells with large fenestrae, but it does not possess stave cells [2]. * **C. Pancreas:** The pancreas consists of acinar cells (exocrine) and Islets of Langerhans (endocrine). It lacks a sinusoidal filtration system. * **D. Gall bladder:** The gallbladder is lined by simple columnar epithelium with microvilli for water absorption; it does not contain vascular stave cells. **High-Yield Clinical Pearls for NEET-PG:** * **"Barrel-hoop" appearance:** This refers to the arrangement of stave cells and the basement membrane (reticular fibers) in the splenic sinusoids. * **Pitting function:** The spleen can "bite" out inclusions (like Heinz bodies or Howell-Jolly bodies) from RBCs as they struggle to pass through stave cell slits [1]. * **Open vs. Closed Circulation:** Stave cells are the gateway in the "open circulation" model of the splenic red pulp.

Q: Canals of Hering are present in which organ?

Liver. The **Canals of Hering** (also known as intrahepatic bile ductules) are anatomical structures located in the **Liver**. They serve as the physiological link between the bile canaliculi (formed by hepatocytes) and the interlobular bile ducts located in the portal triads [1]. **Why Liver is Correct:** The Canals of Hering are lined partially by hepatocytes and partially by specialized epithelial cells called **cholangiocytes**. Their primary function is to transport bile out of the liver lobule [1]. Crucially, for NEET-PG, they are recognized as the **niche for hepatic stem cells** (oval cells), which proliferate during significant liver injury to regenerate hepatocytes or bile duct cells. **Why Other Options are Incorrect:** * **Spleen:** Contains red pulp, white pulp, and sinusoids, but no biliary structures. * **Lymph node:** Characterized by a cortex (follicles), paracortex, and medulla; it contains lymphatic sinuses, not bile canals. * **Bone marrow:** Composed of hematopoietic cords and venous sinusoids; it is the site of blood cell production, unrelated to the biliary system. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** They are found at the periphery of the liver lobule, crossing the limiting plate. * **Stem Cell Niche:** They contain "Oval cells," which are bipotential stem cells. * **Pathology:** In Primary Biliary Cholangitis (PBC), the small bile ductules including the Canals of Hering are often the target of immunological destruction. * **Direction of Flow:** Remember that in a liver lobule, **blood flows centripetally** (toward the central vein), while **bile flows centrifugally** (toward the portal triad via Canals of Hering) [1].

Q: What are the most predominant cells found in the pars nervosa?

Pituicytes. The pituitary gland (hypophysis) is divided into the **Adenohypophysis** (Anterior Pituitary) and the **Neurohypophysis** (Posterior Pituitary). The **Pars Nervosa** is the main bulk of the neurohypophysis. **Why Pituicytes are correct:** Unlike the anterior pituitary, the pars nervosa does not contain glandular secretory cells. Instead, it consists of unmyelinated axons of neurosecretory neurons (whose cell bodies reside in the hypothalamus) and specialized glial cells called **Pituicytes** [1]. Pituicytes are the most predominant cell type in this region; they are star-shaped (astrocytic) cells that provide structural support and regulate the release of hormones (Oxytocin and ADH) from the axonal terminals [3]. **Analysis of Incorrect Options:** * **Options A, B, and D (Basophils, Acidophils, and Chromophobes):** These cells are found exclusively in the **Pars Distalis** (Anterior Pituitary) [2]. * **Acidophils** include Somatotrophs (GH) and Lactotrophs (Prolactin) [2]. * **Basophils** include Corticotrophs (ACTH), Thyrotrophs (TSH), and Gonadotrophs (FSH/LH) [2]. * **Chromatophobes** are cells that have depleted their granules or are undifferentiated stem cells. **High-Yield Facts for NEET-PG:** * **Herring Bodies:** These are dilated terminal portions of axons in the pars nervosa containing neurosecretory granules (ADH and Oxytocin). * **Origin:** The Pars Nervosa develops from **neuroectoderm** (down-growth of the hypothalamus), whereas the Adenohypophysis develops from **Rathke’s pouch** (oral ectoderm). * **Hormone Storage:** The posterior pituitary does *not* synthesize hormones; it only stores and releases hormones produced in the Supraoptic and Paraventricular nuclei of the hypothalamus [1].

Q: Lacis cells are found in which organ?

Kidney. **Explanation:** **Lacis cells** (also known as **Polkissen cells** or extraglomerular mesangial cells) are a vital component of the **Juxtaglomerular Apparatus (JGA)** located in the **Kidney** [1]. They are situated in the triangular space between the afferent arteriole, the efferent arteriole, and the macula densa. While their exact function is still being researched, they are believed to facilitate signaling between the macula densa and the juxtaglomerular cells, playing a role in the tubuloglomerular feedback mechanism and the regulation of blood pressure via the Renin-Angiotensin-Aldosterone System (RAAS) [1]. **Analysis of Options:** * **Brain (Incorrect):** The brain contains specialized cells like neurons and glial cells (astrocytes, microglia, ependymal cells). It does not contain Lacis cells. * **Liver (Incorrect):** The liver is characterized by hepatocytes, Kupffer cells (macrophages), and Ito cells (stellate cells). It lacks the JGA structure where Lacis cells reside. * **Kidney (Correct):** As part of the JGA, Lacis cells are essential for renal autoregulation [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Components of JGA:** 1. Macula Densa (Distal convoluted tubule), 2. Juxtaglomerular cells (Modified smooth muscle of afferent arteriole), 3. Lacis cells (Extraglomerular mesangial cells) [1]. * **JG Cells:** These are the primary site for **Renin** storage and secretion [1]. * **Macula Densa:** Acts as a **chemoreceptor** sensing sodium chloride (NaCl) concentrations in the tubular fluid [2]. * **Lacis Cells Staining:** They are light-staining cells that are continuous with the intraglomerular mesangial cells.

Q: Deiters cells are present in which structure?

Organ of Corti. **Explanation:** **Deiters’ cells**, also known as **outer phalangeal cells**, are specialized supporting cells located within the **Organ of Corti** in the cochlea of the inner ear [1]. They are situated beneath the outer hair cells (OHCs). Each Deiters’ cell has a cup-shaped body that supports the base of an OHC and a long apical process (phalangeal process) that extends upward to form part of the **reticular lamina**. This structural arrangement is crucial for maintaining the mechanical stability of the sensory epithelium during sound transduction. **Analysis of Options:** * **Option A (Correct):** The Organ of Corti is the sensory organ for hearing, located on the basilar membrane [1]. It contains hair cells and various supporting cells, including Deiters’, Hensen’s, Claudius, and Pillar cells. * **Option B (Incorrect):** While the Organ of Corti is *located within* the Scala media (the cochlear duct), Deiters’ cells are specifically a histological component of the Organ of Corti itself, making Option A the more precise anatomical answer. * **Option C & D (Incorrect):** The pharynx and larynx are parts of the upper respiratory and digestive tracts and do not contain these specialized neuroepithelial supporting cells. **High-Yield Facts for NEET-PG:** * **Reticular Lamina:** Formed by the phalangeal processes of Deiters’ cells and the heads of pillar cells; it acts as a barrier separating endolymph from the underlying cortilymph. * **Other Supporting Cells:** * **Hensen’s cells:** Tall cells lateral to Deiters’ cells. * **Pillar cells:** Form the Tunnel of Corti. * **Clinical Pearl:** Damage to the Organ of Corti (including hair cells and supporting Deiters’ cells) due to loud noise or ototoxic drugs leads to **Sensorineural Hearing Loss (SNHL)**.

Q: Plasma cells are a constituent of which type of tissue?

Connective tissue. ### Explanation **Correct Answer: D. Connective tissue** **1. Why Connective Tissue is Correct:** Plasma cells are specialized immune cells derived from **B-lymphocytes** [2]. They are a key component of the **Connective Tissue Proper**, specifically categorized as "wandering" or "transient" cells [3]. Their primary function is the synthesis and secretion of large quantities of antibodies (immunoglobulins) into the extracellular matrix to combat pathogens [1]. Histologically, they are easily identified by their eccentric nucleus and a "cartwheel" or "clock-face" chromatin pattern. **2. Why Other Options are Incorrect:** * **A. Nervous tissue:** Composed primarily of neurons and neuroglia (astrocytes, oligodendrocytes, etc.). While the CNS has specialized immune cells (microglia), plasma cells are not native constituents. * **B. Muscular tissue:** Consists of specialized contractile cells (myocytes). Its primary function is movement and thermogenesis, not immune secretion. * **C. Epithelial tissue:** Characterized by closely packed cells with minimal extracellular matrix. While plasma cells are often found in the *Lamina Propria* (the connective tissue layer immediately beneath the epithelium), they are not part of the epithelium itself [1]. **3. NEET-PG High-Yield Clinical Pearls:** * **Histological Hallmark:** Plasma cells exhibit a prominent **perinuclear halo** (clear zone), which represents a highly developed Golgi apparatus required for antibody packaging. * **Russell Bodies:** These are eosinophilic, large cytoplasmic inclusions representing accumulated immunoglobulins within a plasma cell. * **Clinical Correlation:** A malignancy of plasma cells is known as **Multiple Myeloma**, characterized by the "M-spike" on serum electrophoresis and "punched-out" lytic lesions on X-ray. * **Location:** They are most abundant in the connective tissue of the gastrointestinal and respiratory tracts (sites of pathogen entry) [1].

Q: What is the perichondrial ring?

A structure seen around the epiphyseal plate.. ### Explanation **1. Why Option B is Correct:** The **Perichondrial Ring (of LaCroix)** is a dense fibrous connective tissue band that encircles the periphery of the **epiphyseal plate** (growth plate). It is continuous with the periosteum of the metaphysis and the perichondrium of the epiphysis. Its primary function is to provide **mechanical support** to the relatively weak physis, acting like a "hoop" that prevents the growth plate from widening or displacing under shear and compressive forces. **2. Why the Other Options are Incorrect:** * **Option A:** The structure around the foramen magnum is the *occipital bone* and associated ligaments (like the alar or apical ligaments), not a perichondrial ring. * **Option C:** This structure is **most prominent in children** and adolescents during the period of active skeletal growth [1]. Once the epiphyseal plate ossifies and closes in adulthood, the perichondrial ring disappears. * **Option D:** The shear strength of the perichondrial ring actually **decreases with age** (specifically during the pubertal growth spurt), making the growth plate more susceptible to injuries like Slipped Capital Femoral Epiphysis (SCFE). **3. Clinical Pearls & High-Yield Facts:** * **Two Components:** The ring consists of a fibrous part (Ring of LaCroix) and a cellular part (**Groove of Ranvier**). * **Groove of Ranvier:** This contains osteoblasts and chondroblasts responsible for the **latitudinal (width) growth** of the physis [1]. * **Clinical Significance:** Weakness in this ring is a key factor in **Salter-Harris fractures** and **SCFE**. * **NEET-PG Tip:** If a question asks about the structure responsible for the *increase in diameter* of the growth plate, the answer is the Groove of Ranvier/Perichondrial Ring.

Q: Tattooing colors the skin permanently because pigmented dyes are injected into which layer of the skin?

Dermis (Reticular layer). The permanence of a tattoo depends entirely on the depth at which the pigment is deposited. For a tattoo to be lasting, the dye must reach the **Dermis**, specifically the **Reticular layer**. [1] **Why the Dermis is the correct answer:** The epidermis undergoes constant renewal through a process called desquamation, where cells move from the basal layer to the surface and are shed every 28–30 days. [1] If ink were placed in the epidermis, it would disappear within a month. In contrast, the dermis does not shed. When ink is injected into the dermis, it is engulfed by **dermal macrophages** and fibroblasts or trapped within the dense network of collagen fibers in the reticular layer. [1] Because these cells and fibers are stable, the pigment remains visible through the translucent epidermis permanently. **Why the other options are incorrect:** * **Stratum Corneum:** This is the outermost layer of dead, keratinized cells. It is constantly sloughing off; ink here would wash away in days. [1] * **Stratum Lucidum:** This layer is only found in thick skin (palms and soles). Like all epidermal layers, it is subject to turnover and shedding. * **Stratum Granulosum:** This is a middle layer of the epidermis. Cells here are destined to become keratinized and shed, making it unsuitable for permanent pigmentation. **NEET-PG High-Yield Pearls:** * **Skin Layers:** Remember the mnemonic **"C**ome **L**et's **G**et **S**un **B**urned" (Corneum, Lucidum, Granulosum, Spinosum, Basale). [1] * **Dermal Anatomy:** The dermis has two layers: the superficial **Papillary layer** (loose CT) and the deeper, thicker **Reticular layer** (dense irregular CT). Tattoo ink resides primarily in the reticular layer. [1] * **Clinical Correlation:** Laser tattoo removal works by breaking down these large ink particles into smaller fragments that the lymphatic system can finally carry away.

Question 1

Fenestrations are seen in which vascular layer?

Accepted Answer

Endothelium

Answer

Internal elastic lamina

Answer

External elastic lamina

Answer

Tunica media

Question 2

Which one of the following sensory receptors is found in the epidermis?

Accepted Answer

Meissner's corpuscles

Answer

Merkel disc

Answer

Ruffini ending

Answer

Pacinian corpuscles

Question 3

Stave cells are seen in which organ?

Accepted Answer

Spleen

Answer

Liver

Answer

Pancreas

Answer

Gall bladder

Question 4

Canals of Hering are present in which organ?

Accepted Answer

Liver

Answer

Spleen

Answer

Lymph node

Answer

Bone marrow

Question 5

What are the most predominant cells found in the pars nervosa?

Accepted Answer

Pituicytes

Answer

Basophilic cells

Answer

Acidophilic cells

Answer

Chromatophobe cells

Question 6

Lacis cells are found in which organ?

Accepted Answer

Kidney

Answer

Brain

Answer

Liver

Answer

None of the above

Question 7

Deiters cells are present in which structure?

Accepted Answer

Organ of Corti

Answer

Scala media

Answer

Pharynx

Answer

Larynx

Question 8

Plasma cells are a constituent of which type of tissue?

Accepted Answer

Connective tissue

Answer

Nervous tissue

Answer

Muscular tissue

Answer

Epithelial tissue

Question 9

What is the perichondrial ring?

Accepted Answer

A structure seen around the epiphyseal plate.

Answer

A structure seen around the foramen magnum.

Answer

A structure that is more prominent in adults.

Answer

A structure whose shear strength increases with age.

Question 10

Tattooing colors the skin permanently because pigmented dyes are injected into which layer of the skin?

Accepted Answer

Dermis (Reticular layer)

Answer

Stratum Lucidum

Answer

Stratum Granulosum

Answer

Stratum Corneum

Histology — MCQs

Histology — MCQs

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