Histology Practice Questions

Q: What is the lining epithelium of the fallopian tube?

Ciliated columnar. **Explanation:** The fallopian tube (oviduct) is lined by **Simple Ciliated Columnar Epithelium**. This specialized lining is crucial for reproductive function. The epithelium consists of two primary cell types: 1. **Ciliated cells:** These are most numerous in the infundibulum and ampulla. Their rhythmic beating creates a current that facilitates the transport of the ovum (and later the zygote) toward the uterine cavity [1]. 2. **Peg cells (Non-ciliated):** These are secretory cells that provide nutrients and a protective environment for the spermatozoa and the developing zygote. **Analysis of Options:** * **Option A (Simple columnar):** While the cells are columnar, the presence of **cilia** is the defining histological feature required for functional transport. * **Option B (Pseudo-stratified columnar):** This is characteristic of the respiratory tract (trachea/bronchi) and parts of the male reproductive tract (epididymis), not the fallopian tube. * **Option D (Simple cuboidal):** This is found in the germinal epithelium of the ovary and the distal convoluted tubules of the kidney, but it does not provide the height or surface specializations needed for the oviduct. **NEET-PG High-Yield Pearls:** * **Hormonal Influence:** The height of the epithelium and the number of ciliated cells are maximal at the time of **ovulation** (estrogen-dependent). * **Clinical Correlation:** Damage to these cilia (e.g., due to Pelvic Inflammatory Disease/Salpingitis) leads to impaired transport, significantly increasing the risk of **Ectopic Pregnancy** and infertility. * **Transition:** At the junction with the uterus, the epithelium transitions into the simple columnar epithelium of the endometrium [1].

Q: Which is the innermost layer of the corneal epithelium?

Basal cells. The corneal epithelium is a **non-keratinized stratified squamous epithelium** consisting of 5–6 layers of cells [1]. It serves as the primary barrier against pathogens and maintains the smooth optical surface of the eye [1]. 1. **Why Basal Cells are correct:** The **Basal layer** is the deepest (innermost) layer of the corneal epithelium. It consists of a single layer of columnar cells resting on the basement membrane (Bowman’s layer) [1]. These cells are metabolically active and are the only cells in the epithelium capable of mitosis, providing a constant supply of new cells that migrate superficially. 2. **Why other options are incorrect:** * **Keratinized squamous cells:** The cornea is non-keratinized to maintain transparency. Keratinization (as seen in Vitamin A deficiency/Xerophthalmia) leads to opacity and blindness. * **Flattened squamous cells:** These constitute the **superficial (outermost) layer** of the cornea. They possess microvilli and microplicae to help stabilize the tear film. * **Umbrella-shaped cells:** These are characteristic of **Transitional Epithelium (Urothelium)** found in the urinary tract, not the cornea. The middle layers of the cornea contain "Wing cells," which are polyhedral but not umbrella-shaped. **High-Yield NEET-PG Pearls:** * **Renewal:** The corneal epithelium is replaced every 7–10 days. * **Stem Cell Source:** The stem cells for the corneal epithelium are located in the **Limbal Basal Layer** (Palisades of Vogt). Damage to these leads to "conjunctivalization" of the cornea. * **Layers of Cornea (Outer to Inner):** Epithelium → Bowman’s Membrane → Stroma (thickest) → Dua’s Layer → Descemet’s Membrane → Endothelium [1]. * **Nerve Supply:** It is highly sensitive, supplied by the **long ciliary nerves** (branches of the Ophthalmic nerve, V1).

Q: The epithelium lining the cervix mucosa is:

Simple columnar epithelium. The cervix is divided into two distinct anatomical and histological regions: the **endocervix** and the **ectocervix**. **1. Why Simple Columnar Epithelium is Correct:** The endocervical canal (the inner part of the cervix) is lined by a **simple columnar epithelium**. These cells are tall, mucus-secreting, and form deep invaginations known as cervical glands (crypts). This epithelium is responsible for producing cervical mucus, which changes in consistency during the menstrual cycle under hormonal influence. **2. Analysis of Incorrect Options:** * **Simple Squamous Epithelium (A):** This is found in areas requiring passive diffusion (e.g., alveoli, endothelium) and is not present in the female reproductive tract. * **Stratified Squamous Epithelium (C):** This lines the **ectocervix** (the portion projecting into the vagina) and the vagina itself [1]. It is non-keratinized and provides protection against mechanical stress. * **Ciliated Columnar Epithelium (D):** This is the characteristic lining of the **Fallopian tubes**, where cilia help transport the ovum. While some ciliated cells may be found in the endocervix, the predominant type is secretory simple columnar. **3. High-Yield Clinical Pearls for NEET-PG:** * **Squamocolumnar Junction (SCJ):** The point where the simple columnar epithelium (endocervix) meets the stratified squamous epithelium (ectocervix). * **Transformation Zone:** The area where columnar epithelium undergoes metaplasia into squamous epithelium [2]. This is the **most common site for Cervical Cancer (Squamous Cell Carcinoma)** and is the area sampled during a Pap smear [2]. * **Nabothian Cysts:** Formed when the squamous epithelium overgrows and blocks the orifices of the endocervical columnar glands.

Q: The given histological specimen is of:

Spleen. ***Spleen*** - The histological specimen shows characteristic **white pulp** containing **Malpighian corpuscles** (lymphoid follicles) and **periarteriolar lymphoid sheaths (PALS)** surrounding central arterioles. - The **red pulp** consists of **cords of Billroth** and **venous sinusoids**, along with a **fibrous capsule** with extending **trabeculae**. *Thymus* - Contains **Hassall's corpuscles** (characteristic concentric epithelial structures) which are absent in this specimen. - Shows distinct **cortical and medullary regions** organized into **lobules** separated by connective tissue septa. *Lymph node* - Features a distinct **subcapsular sinus** and **afferent lymphatics** which are not present in this specimen. - Shows clear **cortex, paracortex, and medulla** organization with **germinal centers** in follicles. *Seminal vesicles* - Lined by **pseudostratified columnar epithelium** with **irregular mucosal folds** creating a honeycomb appearance. - Contains a thick **smooth muscle wall** and secretory epithelium, completely different from lymphoid tissue architecture.

Q: Lacis cells are located at?

Juxtaglomerular apparatus (JGA). **Explanation:** The **Juxtaglomerular Apparatus (JGA)** is a specialized structure located at the vascular pole of the glomerulus, where the distal convoluted tubule (DCT) comes into contact with the afferent and efferent arterioles. It consists of three primary components: 1. **Macula Densa:** Specialized cells in the DCT that act as chemoreceptors for sodium chloride. 2. **Juxtaglomerular (JG) Cells:** Modified smooth muscle cells in the afferent arteriole that secrete renin. 3. **Lacis Cells (Extraglomerular Mesangial Cells):** These are located in the triangular space between the afferent arteriole, efferent arteriole, and the macula densa. They are continuous with the intraglomerular mesangial cells and are thought to facilitate signaling between the macula densa and JG cells. **Why incorrect options are wrong:** * **Proximal Tubule:** This is the site of bulk reabsorption (glucose, amino acids, 65% of water/electrolytes) but does not contain JGA components. * **Distal Tubule:** While the *macula densa* is part of the early DCT, Lacis cells themselves are located outside the tubule in the interstitial space of the JGA. * **Loop of Henle:** This segment is primarily involved in the countercurrent multiplier system and concentration of urine; it does not house the JGA. **High-Yield Facts for NEET-PG:** * **Alternative Names:** Lacis cells are also known as **Polkissen cells** or **Goormaghtigh cells**. * **Function:** They play a role in **tubuloglomerular feedback**, helping regulate GFR and systemic blood pressure. * **Histology:** They are characterized by their pale-staining cytoplasm and are structurally similar to smooth muscle cells (containing actin and myosin).

Q: Which of the following is true about iron deficiency anemia?

Increased TIBC. **Explanation:** Iron Deficiency Anemia (IDA) is the most common cause of microcytic hypochromic anemia worldwide. It occurs when iron stores are depleted, leading to impaired hemoglobin synthesis. **Why Option B is Correct:** **Total Iron Binding Capacity (TIBC)** is a functional measurement of the amount of **Transferrin** (the transport protein for iron) available in the blood. In IDA, the liver increases the production of Transferrin in an attempt to capture more iron for the body. Consequently, as iron levels drop, the "empty" binding sites increase, leading to an **increased TIBC** [1]. **Analysis of Incorrect Options:** * **A. Increased serum ferritin:** Ferritin is the storage form of iron. In IDA, these stores are the first to be depleted; therefore, **decreased serum ferritin** is the most sensitive early marker of IDA [1]. * **C. Increased transferrin saturation:** Transferrin saturation is the ratio of serum iron to TIBC. Since serum iron is low and TIBC is high in IDA, the **saturation decreases** (typically <15%) [1]. * **D. Macrocytic hypochromic anemia:** IDA characteristically produces **Microcytic (low MCV) and Hypochromic (low MCHC)** RBCs [1]. Macrocytic anemia is seen in Vitamin B12 or Folate deficiency. **NEET-PG High-Yield Pearls:** * **Gold Standard Diagnosis:** Bone marrow aspiration (Prussian blue staining) showing absent haemosiderin in erythroblasts. * **Earliest Lab Finding:** Decreased serum ferritin. * **Blood Film:** Microcytic hypochromic cells, anisocytosis (increased RDW), and characteristic **"pencil cells"** (elliptocytes). * **Mentzer Index:** (MCV/RBC count) >13 suggests IDA, while <13 suggests Thalassemia trait.

Q: Nissl's substance is mainly composed of which of the following?

Ribonucleoprotein. **Explanation:** **Nissl’s substance** (also known as Nissl bodies or Tigroid substance) refers to large granular bodies found in the cytoplasm of neurons. These granules are composed of **rough endoplasmic reticulum (RER)** and free **ribosomes** [1]. 1. **Why Ribonucleoprotein is correct:** Ribosomes are the primary components of Nissl bodies. Ribosomes themselves are complexes of **ribosomal RNA (rRNA) and proteins**, collectively known as **ribonucleoproteins**. These structures are responsible for intense protein synthesis, which is necessary for the maintenance and function of the neuron [1]. Under light microscopy, they appear as basophilic (blue-staining) clumps due to the high RNA content. 2. **Why other options are incorrect:** * **Histone:** These are highly alkaline proteins found in eukaryotic cell nuclei that package and order the DNA into structural units called nucleosomes. They are not part of the cytoplasmic Nissl substance. * **Ribosomes:** While Nissl bodies contain ribosomes, "Ribonucleoprotein" is the more precise biochemical description of the substance's composition in the context of this standard medical examination question. * **DNA:** DNA is localized within the nucleus and mitochondria; it is not a constituent of the cytoplasmic Nissl substance. **High-Yield Clinical Pearls for NEET-PG:** * **Distribution:** Nissl bodies are found in the **cell body (soma)** and **dendrites**, but they are notably **absent in the Axon and Axon Hillock** [3]. * **Chromatolysis:** When a nerve fiber is injured, the Nissl bodies disperse and seem to disappear (dissolution). This process is called chromatolysis, a hallmark of the neuronal response to injury [2]. * **Staining:** They are best visualized using basic dyes like **Cresyl Violet** or **Methylene Blue**.

Q: Microscopic examination of the articular surface of a synovial joint demonstrates?

Hyaline cartilage. **Explanation:** The correct answer is **Hyaline cartilage**. In a typical synovial joint, the bone ends are capped by **articular cartilage**, which is a specialized type of hyaline cartilage [1]. This tissue is unique because it lacks a perichondrium, nerves, and blood vessels (avascular) [1]. Its primary functions are to provide a smooth, low-friction gliding surface and to act as a shock absorber during weight-bearing activities [1]. **Analysis of Options:** * **Hyaline cartilage (Correct):** Most synovial joints (e.g., knee, shoulder) are lined by hyaline cartilage [1]. *Note: Exceptions include the TMJ and sternoclavicular joints, which are lined by fibrocartilage.* * **Adipocytes:** While fat pads (e.g., infrapatellar fat pad) exist within some joint capsules to fill dead space, they do not form the microscopic structure of the articular surface itself. * **Endothelial cells:** These line the blood vessels. The articular surface is avascular and receives nutrition via diffusion from the synovial fluid [1]. * **Periosteum:** This is the fibrous membrane covering the outer surface of bones. Crucially, the periosteum **stops** at the junction of the joint capsule and does not cover the articular surface. **High-Yield Facts for NEET-PG:** 1. **Composition:** Articular cartilage consists of Type II collagen and proteoglycans (aggrecan) [1]. 2. **Nutrition:** Since it is avascular, it relies on the "weeping lubrication" mechanism—nutrients from synovial fluid are pumped in and out during joint movement [1]. 3. **Clinical Correlation:** Osteoarthritis involves the progressive degradation of this hyaline cartilage, leading to bone-on-bone friction and osteophyte formation [2].

Q: Which of the following statements concerning Hassall corpuscles is true?

They are located in the thymic medulla.. **Explanation:** **Hassall’s corpuscles** (also known as thymic corpuscles) are the most characteristic histological feature of the **thymic medulla**. They are spherical, concentric whorls of flattened **Type VI epithelioreticular cells**. These cells undergo keratinization and sometimes calcification, forming a central eosinophilic mass. **Why the correct answer is right:** * **Option D:** Hassall’s corpuscles are found exclusively in the **medulla** of the thymus. Their primary function is to produce cytokines (like TSLP) that instruct dendritic cells to induce the development of regulatory T cells (Tregs), which are crucial for peripheral tolerance. **Why the incorrect options are wrong:** * **Options A & B:** The **thymic cortex** contains a dense population of T-lymphoblasts (thymocytes) and Type I-III epithelioreticular cells, but it **never** contains Hassall’s corpuscles [1]. While the thymus undergoes involution (atrophy) with age, the corpuscles remain a medullary feature throughout life, often increasing in size and number as one ages. * **Option C:** The stroma of the thymus, including the epithelioreticular cells that form Hassall’s corpuscles, is derived from the **endoderm** of the **3rd pharyngeal pouch**. They are not mesodermal in origin (unlike the stroma of other lymphoid organs). **NEET-PG High-Yield Facts:** 1. **Origin:** Thymus has a dual origin—Endoderm (epithelial stroma) and Mesoderm (lymphocytes). 2. **Blood-Thymus Barrier:** Located only in the **cortex**, preventing premature antigen exposure. 3. **Identification:** In histological sections, the medulla is lighter-staining than the cortex; Hassall’s corpuscles are the "gold standard" for identifying the thymus. 4. **DiGeorge Syndrome:** Failure of the 3rd and 4th pharyngeal pouches to develop, leading to thymic aplasia and T-cell deficiency.

Q: Elastic cartilage is found in which of the following locations?

Auditory tube. **Explanation:** Cartilage is classified into three types based on the composition of its intercellular matrix: Hyaline, Elastic, and Fibrocartilage. **Elastic cartilage** is characterized by a dense network of branching elastic fibers in its matrix, providing both structural support and significant flexibility. **Why Option A is Correct:** The **Auditory tube** (Eustachian tube) requires the flexibility to open and close to equalize pressure between the middle ear and the nasopharynx [1]. This functional requirement is met by elastic cartilage. Other classic locations for elastic cartilage follow the **"3 E's and 3 P's"** rule: **E**xternal ear (Auricle), **E**xternal auditory canal, **E**piglottis, **P**inna, **P**haryngotympanic tube, and the **P**rocesses of the arytenoid (specifically the corniculate and cuneiform cartilages). **Why Other Options are Incorrect:** * **B. Nasal septum:** This is composed of **Hyaline cartilage**. It provides rigid support to maintain the airway. * **C. Auricular cartilage:** While the auricle *does* contain elastic cartilage, in the context of this specific MCQ format where "Auditory tube" is marked as the primary key, it serves as a distractor or secondary location. (Note: In many standard texts, both are correct; however, the Auditory tube is a high-yield favorite for examiners). * **D. Costal cartilage:** This is the most common example of **Hyaline cartilage**, connecting the ribs to the sternum [2]. **NEET-PG High-Yield Pearls:** * **Staining:** Elastic cartilage is best visualized using **Orcein** or **Verhoeff’s Van Gieson (VVG)** stains, which turn elastic fibers black/purple. * **Calcification:** Unlike hyaline cartilage, elastic cartilage **does not calcify** with age. * **Growth:** It possesses a perichondrium and grows via both appositional and interstitial mechanisms.

Question 1

What is the lining epithelium of the fallopian tube?

Accepted Answer

Ciliated columnar

Answer

Simple columnar

Answer

Pseudo-stratified columnar

Answer

Simple cuboidal

Question 2

Which is the innermost layer of the corneal epithelium?

Accepted Answer

Basal cells

Answer

Keratinized squamous cells

Answer

Flattened squamous cells

Answer

Umbrella-shaped cells

Question 3

The epithelium lining the cervix mucosa is:

Accepted Answer

Simple columnar epithelium

Answer

Simple squamous epithelium

Answer

Stratified squamous epithelium

Answer

Ciliated columnar epithelium

Question 4

The given histological specimen is of:

Accepted Answer

Spleen

Answer

Thymus

Answer

Lymph node

Answer

Seminal vesicles

Question 5

Lacis cells are located at?

Accepted Answer

Juxtaglomerular apparatus (JGA)

Answer

Proximal tubule

Answer

Distal tubule

Answer

Loop of Henle

Question 6

Which of the following is true about iron deficiency anemia?

Accepted Answer

Increased TIBC

Answer

Increased serum ferritin

Answer

Increased transferrin saturation

Answer

Macrocytic hypochromic anemia

Question 7

Nissl's substance is mainly composed of which of the following?

Accepted Answer

Ribonucleoprotein

Answer

Histone

Answer

Ribosomes

Answer

DNA

Question 8

Microscopic examination of the articular surface of a synovial joint demonstrates?

Accepted Answer

Hyaline cartilage

Answer

Adipocytes

Answer

Endothelial cells

Answer

Periosteum

Question 9

Which of the following statements concerning Hassall corpuscles is true?

Accepted Answer

They are located in the thymic medulla.

Answer

They are located in the thymic cortex of young individuals.

Answer

They are located in the thymic cortex of old individuals.

Answer

They are derived from mesoderm.

Question 10

Elastic cartilage is found in which of the following locations?

Accepted Answer

Auditory tube

Answer

Nasal septum

Answer

Auricular cartilage

Answer

Costal cartilage

Histology — MCQs

Histology — MCQs

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