Histology Practice Questions

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: 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: 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.

Q: What is the best marker for iron deficiency?

Serum ferritin. **Explanation:** **Serum ferritin** is considered the most reliable and sensitive biochemical marker for diagnosing iron deficiency. Ferritin is the primary intracellular storage protein for iron. Since serum ferritin levels are directly proportional to total body iron stores, a low level is highly specific for iron deficiency anemia (IDA), often decreasing before changes in hemoglobin or red cell morphology occur. [1] **Analysis of Incorrect Options:** * **Serum Iron:** This measures the amount of iron circulating in the blood bound to transferrin. It is a poor marker because it fluctuates significantly throughout the day (diurnal variation) and can be affected by recent dietary intake or infection. * **Total Iron Binding Capacity (TIBC):** This measures the blood's capacity to bind iron with transferrin. While TIBC increases in iron deficiency, it is an indirect measure and can be influenced by liver function and nutritional status (e.g., pregnancy or oral contraceptives). * **Transferrin Saturation:** This is the ratio of serum iron to TIBC. While it decreases in IDA, it is less sensitive than ferritin because it relies on serum iron levels, which are inherently unstable. **NEET-PG High-Yield Pearls:** * **Gold Standard:** While serum ferritin is the best *non-invasive* test, the absolute gold standard for assessing iron stores is a **Bone Marrow Aspiration** (Prussian Blue staining), though it is rarely performed for simple IDA. * **The "Acute Phase" Caveat:** Ferritin is an **acute-phase reactant**. In the presence of inflammation, malignancy, or liver disease, ferritin levels may be falsely elevated even if the patient is iron deficient. * **Early Marker:** The very first biochemical change in developing iron deficiency is a **decrease in serum ferritin**. [1]

Q: Which one of the following statements about cilia is true?

They contain ciliary dynein arms.. ### Explanation **1. Why the Correct Answer is Right:** Cilia are motile, hair-like projections of the plasma membrane. The core of a motile cilium is the **axoneme**, which consists of a central pair of microtubules surrounded by nine peripheral doublets (**9 + 2 arrangement**) [2]. The movement of cilia is powered by **ciliary dynein arms** (adenosine triphosphatase/ATPase) [1]. These arms are attached to the 'A' microtubule of each doublet and reach out to the 'B' microtubule of the adjacent doublet, facilitating the sliding motion required for ciliary beating. **2. Analysis of Incorrect Options:** * **Option A:** Motile cilia have a **9 + 2** configuration [2]. A **9 + 0** configuration is characteristic of **primary (non-motile) cilia**, which lack the central pair and function as sensory receptors. * **Option B:** The **axoneme** is the structural backbone of the cilium; saying they do not contain one is anatomically incorrect. * **Option D:** Cilia are structurally distinct from centrioles. While the **basal body** (which anchors the cilium) has a 9 + 0 triplet arrangement similar to a centriole, the cilium itself has a doublet arrangement (9 + 2 or 9 + 0). **3. Clinical Pearls & High-Yield Facts:** * **Kartagener Syndrome:** A subset of Primary Ciliary Dyskinesia (PCD) caused by a **deficiency in dynein arms**. Clinical triad: *Situs inversus, chronic sinusitis, and bronchiectasis* [3]. * **Infertility:** Ciliary dysfunction leads to male infertility (immotile spermatozoa) and female subfertility (impaired ovum transport in fallopian tubes). * **Location:** Motile cilia are primarily found in the respiratory epithelium (mucociliary escalator) and the female reproductive tract [3].

Q: Which of the following is NOT a feature found in the cerebellum?

Betz cells. **Explanation:** The correct answer is **Betz cells** because these are characteristic features of the **Cerebrum**, not the Cerebellum. **1. Why Betz cells is the correct answer:** Betz cells are giant pyramidal neurons located in **Layer V (Internal Pyramidal Layer)** of the primary motor cortex (Brodmann area 4) of the cerebrum. They are the largest neurons in the central nervous system and their axons form part of the corticospinal tract. **2. Why the other options are incorrect:** The cerebellum has a highly organized three-layered cortex (Molecular, Purkinje, and Granular layers) containing specific fibers and cells [1]: * **Purkinje cells:** These are the large, flask-shaped inhibitory neurons found in the middle layer of the cerebellar cortex [1]. They represent the sole output from the cerebellar cortex to the deep cerebellar nuclei [1]. * **Climbing fibers:** These originate from the **inferior olivary nucleus** and wrap around the dendrites of Purkinje cells, providing powerful excitatory input [2]. * **Mossy fibers:** These are the main afferent inputs to the cerebellum (from the spinal cord and pons). They synapse with **granule cells** in specialized structures called cerebellar glomeruli [1]. **High-Yield Facts for NEET-PG:** * **Layers of Cerebellar Cortex (Outer to Inner):** Molecular layer $\rightarrow$ Purkinje cell layer $\rightarrow$ Granular layer [1]. * **Inhibitory Cells:** All cells in the cerebellar cortex are inhibitory (GABAergic) EXCEPT for **Granule cells**, which are excitatory (Glutamatergic) [1]. * **Cerebellar Glomerulus:** A complex synaptic junction consisting of a Mossy fiber terminal, Golgi cell axon, and Granule cell dendrites [1]. * **Clinical Correlation:** Damage to the cerebellum leads to **ipsilateral** symptoms like ataxia, intention tremors, and dysmetria (DANISH mnemonic) [2].

Question 1

Canals of Hering are present in which organ?

Accepted Answer

Liver

Answer

Spleen

Answer

Lymph node

Answer

Bone marrow

Question 2

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

Accepted Answer

Pituicytes

Answer

Basophilic cells

Answer

Acidophilic cells

Answer

Chromatophobe cells

Question 3

Paneth cells are characterized by which of the following?

Accepted Answer

A high concentration of zinc

Answer

A higher number of lysosomal enzymes

Answer

A higher concentration of EFR

Answer

Foamy cells

Question 4

All are true about bulbar urethral rupture, except?

Accepted Answer

Floating prostate on per rectal examination

Answer

Perineal hematoma

Answer

Collection of urine in the perineum

Answer

Bleeding per urethra

Question 5

Plasma cells are a constituent of which type of tissue?

Accepted Answer

Connective tissue

Answer

Nervous tissue

Answer

Muscular tissue

Answer

Epithelial tissue

Question 6

A 15-year-old girl presents with a sore throat. She is prescribed an antibiotic that can enter most body tissues but cannot penetrate the blood-brain barrier. Which cell type is primarily responsible for the blood-brain barrier?

Accepted Answer

Endothelial cell

Answer

Astrocyte

Answer

Glial cell

Answer

Macrophage

Question 7

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

Question 8

What is the best marker for iron deficiency?

Accepted Answer

Serum ferritin

Answer

Serum iron

Answer

Total iron binding capacity

Answer

Transferrin saturation

Question 9

Which one of the following statements about cilia is true?

Accepted Answer

They contain ciliary dynein arms.

Answer

They possess a 9 + 0 configuration of microtubules.

Answer

They do not contain an axoneme.

Answer

They are nearly identical to centrioles.

Question 10

Which of the following is NOT a feature found in the cerebellum?

Accepted Answer

Betz cells

Answer

Climbing fibers

Answer

Mossy fibers

Answer

Purkinje cells

Histology — MCQs

Histology — MCQs

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