Histology Practice Questions

Q: The histological section shown in the image, characterized by predominantly serous acini, is best identified as which organ?

Parotid gland. ***Parotid gland*** - The parotid gland is a **purely serous** salivary gland, meaning its secretory acini consist exclusively of serous cells that secrete a watery, enzyme-rich fluid. - It is histologically distinguished by the presence of numerous **striated ducts** and **intercalated ducts** scattered throughout the serous acinar tissue, which helps differentiate it from other salivary glands or the pancreas. *Sublingual salivary gland* - This gland is classified as a **mucous-predominant** gland, meaning the majority of its acini are composed of mucous cells, not serous cells. - It typically features **mucous acini** often capped by serous demilunes, appearing structurally distinct from the purely serous morphology of the parotid gland. *Pancreas* - While the pancreas contains purely serous acini, it is distinguished from the parotid gland by the presence of **Islets of Langerhans** (endocrine tissue) and the absolute absence of striated ducts. - The acini in the pancreas typically show **centroacinar cells**, a feature uniquely characteristic of the pancreatic exocrine system and absent in salivary glands. *Liver* - The liver is organized into **hepatic lobules** (hexagonal structures) rather than acinar glandular units. - Histologically, it consists primarily of **hepatocytes** arranged in plates separated by sinusoids, not secretory acini like those found in salivary glands or the pancreas.

Q: Match each of the following gastrointestinal organs with its distinctive histological feature: Organ Histological Feature 1. Ileum a. Taenia coli 2. Transverse colon b. Villi 3. Esophagus c. Peyer's patches 4. Duodenum d. Non-keratinized stratified squamous epithelium

1-c, 2-a, 3-d, 4-b. ***1-c, 2-a, 3-d, 4-b*** - The **ileum** is histologically distinguished by the presence of **Peyer's patches**, which are large aggregates of lymphoid tissue commonly found in the lamina propria and submucosa. - The **transverse colon** features **taeniae coli**, which are three distinct longitudinal bands of smooth muscle that run along the length of the large intestine. - The **esophagus** is lined by a **non-keratinized stratified squamous epithelium**, which provides protection against mechanical abrasion from food boluses. - The **duodenum** is characterized by the presence of prominent **villi** for nutrient absorption and **Brunner's glands** in the submucosa. *1-a, 2-c, 3-d, 4-b* - Incorrect because the **ileum** contains Peyer's patches (c), not taeniae coli (a). - Incorrect because the **transverse colon** contains taeniae coli (a), not Peyer's patches (c). *1-c, 2-b, 3-a, 4-d* - Incorrect because the **transverse colon** does not possess villi (b), as villi are a characteristic feature of the small intestine for nutrient absorption. - Incorrect because the **esophagus** does not contain taeniae coli (a), as taeniae coli are restricted to the large intestine. *1-d, 2-a, 3-c, 4-b* - Incorrect because the **ileum** is not lined by non-keratinized stratified squamous epithelium (d); that is a feature of the esophagus. - Incorrect because the **esophagus** does not contain Peyer's patches (c), which are specific to the distal small bowel.

Q: What type of tissue predominantly comprises the cervix?

Mainly collagen. The cervix is the lower, cylindrical portion of the uterus, but it differs significantly from the uterine body (corpus) in its histological composition. While the body of the uterus is primarily a muscular organ (myometrium), the **cervix is predominantly a fibrous organ.** [1] **1. Why "Mainly Collagen" is Correct:** The cervical stroma is composed of approximately **85–90% dense collagenous connective tissue**, with only about 10–15% smooth muscle. This high collagen content provides the structural integrity and "firmness" required to keep the cervix closed during pregnancy, supporting the weight of the growing fetus and the amniotic sac. [1] **2. Why Other Options are Incorrect:** * **Option A (Mainly muscle fibers):** This describes the **uterine body**, where smooth muscle is essential for powerful contractions during labor [1]. In the cervix, muscle fibers are sparse and primarily located in the outer circumferential layer. * **Option C (Equal proportions):** This is histologically inaccurate. The transition from the muscular corpus to the fibrous cervix occurs at the internal os, where the muscle content drops sharply. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Cervical Ripening:** During labor, the enzyme **collagenase** breaks down the collagen fibers. This biochemical change (not just muscle contraction) allows the cervix to become soft, thin (effacement), and dilate [2]. * **Epithelial Transition:** The ectocervix is lined by **stratified squamous epithelium**, while the endocervix is lined by **simple columnar epithelium**. The junction between them (Squamocolumnar Junction) is the most common site for cervical cancer. * **Consistency:** On clinical examination, the non-pregnant cervix feels firm (like the **tip of the nose**), whereas, during pregnancy, it softens (Goodell’s sign) due to increased vascularity and collagen remodeling.

Q: Aggrecan is a component of which of the following?

Important component of cartilage. **Explanation:** **Aggrecan** is the most abundant **proteoglycan** found in the extracellular matrix (ECM) of **cartilage** (specifically hyaline and fibrocartilage) [1]. It consists of a core protein to which numerous glycosaminoglycan (GAG) chains—primarily **chondroitin sulfate** and **keratan sulfate**—are covalently attached. These aggrecan molecules bind to a long strand of hyaluronic acid to form massive proteoglycan aggregates [1]. Due to its high negative charge, aggrecan attracts water, providing cartilage with its essential osmotic properties and the ability to resist compressive forces (load-bearing capacity) [1]. **Analysis of Incorrect Options:** * **Option A:** Receptors on platelets are typically glycoproteins (e.g., GpIIb/IIIa or GpIb-IX-V), not large proteoglycans like aggrecan. * **Option B:** While osteoid (unmineralized bone matrix) contains proteoglycans, its primary components are Type I collagen and non-collagenous proteins like Osteocalcin and Osteopontin [2]. Aggrecan is specific to the cartilaginous matrix. * **Option C:** Leukocyte granules contain enzymes (like myeloperoxidase), histamine, or heparin (in basophils), but not aggrecan. **High-Yield Facts for NEET-PG:** * **Cartilage Composition:** Type II collagen provides tensile strength, while Aggrecan provides compressive strength [1]. * **Link Protein:** This protein stabilizes the interaction between the aggrecan core protein and hyaluronan. * **Clinical Correlation:** Degradation of aggrecan by enzymes known as **ADAMTS** (aggrecanases) is a hallmark of early **Osteoarthritis**. * **Marker:** Aggrecan is often used as a marker for chondrocyte differentiation in histology.

Q: What is the cell junction marked by the circle?

Zona adherens. ***Zona adherens*** - Part of the **apical junctional complex** located between zonula occludens and macula adherens, forming a **belt-like junction** around epithelial cells. - Contains **cadherin proteins** and **actin filaments** that provide mechanical strength and maintain cell-to-cell adhesion. *Fascia adherens* - Specific to **cardiac muscle cells** at intercalated discs, not found in typical epithelial tissues. - Functions to anchor **actin filaments** and transmit contractile forces between cardiomyocytes. *Macula adherens* - Also called **desmosomes**, these are **spot-like junctions** located more basally in the apical junctional complex. - Contain **desmosomal cadherins** and **intermediate filaments**, providing strong mechanical adhesion but appearing as discrete spots rather than continuous bands. *Zonula occludens* - The most **apical junction** in the terminal bar, also known as **tight junctions**. - Functions to create a **permeability barrier** and prevent paracellular transport, rather than primarily providing mechanical adhesion.

Q: Nissl substance is found in:

Neuron. **Explanation:** **1. Why the Correct Answer is Right:** Nissl substance (or Nissl bodies) refers to large, granular structures found in the cytoplasm of **neurons**. Ultrastructurally, they are composed of **Rough Endoplasmic Reticulum (RER)** and free ribosomes [1]. Their primary function is high-rate protein synthesis [4], necessary for maintaining the neuron's structure and producing neurotransmitters. They are located in the **cell body (soma)** and **dendrites**, but are characteristically **absent in the axon and the axon hillock** [2]. **2. Why the Other Options are Incorrect:** * **Hepatocytes (B):** While liver cells are rich in RER for albumin synthesis, these organelles are not organized into the specific "Nissl" configuration unique to nervous tissue. * **Cardiocytes (C):** Cardiac muscle cells contain abundant mitochondria and sarcoplasmic reticulum (smooth ER) for energy and calcium handling, but do not contain Nissl bodies. * **Enterocytes (D):** These intestinal epithelial cells are specialized for absorption and secretion; they possess standard organelles but lack the specialized Nissl substance. **3. Clinical Pearls & High-Yield Facts for NEET-PG:** * **Chromatolysis:** This is a high-yield clinical phenomenon where Nissl bodies disperse and disappear from the soma following axonal injury (retrograde degeneration) [3]. It indicates an active attempt at protein synthesis for repair. * **Staining:** Nissl bodies are highly "basophilic" and are best visualized using basic dyes like **Cresyl Violet** or **Methylene Blue**. * **Distribution:** Remember the "Axon Hillock Rule"—the absence of Nissl substance in the axon hillock helps histologists distinguish the axon from dendrites under a microscope [2].

Q: Ectocervix is predominantly lined by which of the following type of epithelium?

Nonkeratinized stratified squamous epithelium. **Explanation:** The cervix is divided into two distinct anatomical and histological regions: the **endocervix** (inner canal) and the **ectocervix** (the portion projecting into the vagina). The **ectocervix** is exposed to the acidic environment and mechanical friction of the vaginal vault. To withstand this "wear and tear," it is lined by **Nonkeratinized Stratified Squamous Epithelium** [2]. This multi-layered epithelium provides a protective barrier, similar to the lining of the vagina and esophagus. **Analysis of Incorrect Options:** * **Option A (Cuboidal):** This is typically found in kidney tubules or glandular ducts, not the cervix. * **Option B (Mucin-secreting columnar):** This is the characteristic lining of the **Endocervix**. These cells secrete mucus to form a cervical plug. * **Option C (Pseudostratified columnar):** This "respiratory-type" epithelium is found in the trachea and bronchi, not the female reproductive tract. **Clinical Pearls for NEET-PG:** 1. **Squamocolumnar Junction (SCJ):** The point where the endocervical columnar epithelium meets the ectocervical squamous epithelium. 2. **Transformation Zone:** The area where columnar cells undergo **metaplasia** into squamous cells [1]. This is the most common site for **Cervical Cancer (Squamous Cell Carcinoma)** and is the area sampled during a **Pap smear** [2]. 3. **Nabothian Cysts:** Formed when squamous epithelium overgrows and blocks the orifices of endocervical columnar glands.

Question 1

The histological section shown in the image, characterized by predominantly serous acini, is
best identified as which organ?

Accepted Answer

Parotid gland

Answer

Sublingual salivary gland

Answer

Pancreas

Answer

Liver

Question 2

Match each of the following gastrointestinal organs with its distinctive histological feature:

Organ Histological Feature

1. Ileum a. Taenia coli

2. Transverse colon b. Villi

3. Esophagus c. Peyer's patches

4. Duodenum d. Non-keratinized stratified squamous
epithelium

Accepted Answer

1-c, 2-a, 3-d, 4-b

Answer

1-a, 2-c, 3-d, 4-b

Answer

1-c, 2-b, 3-a, 4-d

Answer

1-d, 2-a, 3-c, 4-b

Question 3

What type of tissue predominantly comprises the cervix?

Accepted Answer

Mainly collagen

Answer

Mainly muscle fibers

Answer

Equal proportions of muscle and collagen

Answer

None of the above

Question 4

All the following statements are true regarding the pregnant and lactating breast, EXCEPT:

Accepted Answer

There is an increase in the interlobular connective tissue

Answer

The terminal lobular units are most affected during pregnancy

Answer

Cuboidal luminal epithelial cells show vacuolization

Answer

Fat droplets occur in the cytoplasm of the epithelium

Question 5

Aggrecan is a component of which of the following?

Accepted Answer

Important component of cartilage

Answer

Receptor over platelets

Answer

A molecule present in osteoid tissue

Answer

Granules in leukocytes

Question 6

What is the cell junction marked by the circle?

Accepted Answer

Zona adherens

Answer

Fascia adherens

Answer

Macula adherens

Answer

Zonula occludens

Question 7

Rhomboid major is supplied by which type of neuron?

Accepted Answer

Multipolar

Answer

Unipolar

Answer

Pseudounipolar

Answer

Bipolar

Question 8

Goblet cells are present in which of the following structures?

Accepted Answer

Trachea

Answer

Jejunum

Answer

Epididymis

Answer

Ileum

Question 9

Nissl substance is found in:

Accepted Answer

Neuron

Answer

Hepatocytes

Answer

Cardiocytes

Answer

Enterocytes

Question 10

Ectocervix is predominantly lined by which of the following type of epithelium?

Accepted Answer

Nonkeratinized stratified squamous epithelium

Answer

Cuboidal epithelium

Answer

Mucin secreting columnar epithelium

Answer

Pseudostratified columnar epithelium

Histology — MCQs

Histology — MCQs

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