Microscopic Anatomy Practice Questions

Q: In which of the following organs are 'peg cells' characteristically seen?

Fallopian tubes. The **Fallopian tube** (Salpinx/Oviduct) is lined by a simple columnar epithelium consisting of two distinct cell types: **Ciliated cells** and **Non-ciliated (Peg) cells**. [1] 1. **Peg Cells (Correct Answer):** These are narrow, dark-staining, non-ciliated secretory cells. They are called "peg cells" because they appear squeezed between the more numerous ciliated cells. Their primary function is to secrete a nutrient-rich fluid that facilitates the capacitation of spermatozoa and provides nourishment to the ovum and the early zygote. [1] 2. **Ciliated Cells:** These cells possess apical cilia that beat toward the uterus, aiding in the transport of the oocyte and the embryo. [1] **Why other options are incorrect:** * **Vagina:** Lined by non-keratinized stratified squamous epithelium. It lacks glands; lubrication is provided by cervical mucus and transudate from vaginal capillaries. * **Vulva:** Covered by stratified squamous epithelium (keratinized on the labia majora). [2] * **Ovary:** Covered by a single layer of cuboidal cells known as the **Germinal Epithelium of Waldeyer**, which sits on the tunica albuginea. [1] **High-Yield Clinical Pearls for NEET-PG:** * **Hormonal Influence:** The height of the epithelium and the activity of cilia are maximal during **ovulation** (estrogen phase) and decrease during the luteal phase (progesterone phase). * **Site of Fertilization:** Usually occurs in the **Ampulla** of the Fallopian tube. * **Kartagener Syndrome:** Immotile cilia lead to infertility in females due to the inability of Fallopian tube cilia to transport the ovum.

Q: After maturation in the thymus and release into the circulation, T lymphocytes preferentially migrate to which of the following sites?

Paracortex of lymph nodes. ### Explanation The correct answer is **A. Paracortex of lymph nodes.** **Concept:** Lymphoid organs are organized into specific zones populated by either B or T lymphocytes. After maturing in the thymus, T cells enter the circulation and home to **thymus-dependent zones** of secondary lymphoid organs [1], [2]. In the lymph node, this specific region is the **paracortex** (the zone between the outer cortex and the medulla). This area is characterized by the presence of **High Endothelial Venules (HEVs)**, which express specific adhesion molecules (addressins) that allow circulating T cells to extravasate into the node [1]. **Analysis of Incorrect Options:** * **B. Cortical lymphoid nodules:** These are located in the outer cortex and are **thymus-independent zones**. They are primarily composed of B lymphocytes. Primary follicles contain resting B cells, while secondary follicles contain germinal centers for B-cell proliferation. * **C. Hilum of lymph nodes:** This is the structural exit point where efferent lymphatic vessels and blood vessels leave/enter the node. It is not a site of lymphocyte sequestration or functional organization. * **D. Lymphoid nodules of the tonsils:** Similar to the nodules in lymph nodes, these are B-cell rich areas. While tonsils do have T-cell zones (interfollicular regions), the paracortex of the lymph node is the classic, high-yield example of a T-cell dependent zone. **NEET-PG High-Yield Pearls:** 1. **Thymus-Dependent Zones:** Paracortex (Lymph Node), Periarteriolar Lymphoid Sheaths (PALS) in the Spleen, and interfollicular areas in Peyer’s patches. 2. **DiGeorge Syndrome:** Due to thymic hypoplasia, the paracortex of lymph nodes and PALS of the spleen will be depleted/underdeveloped. 3. **HEVs:** Found in all secondary lymphoid organs except the spleen [1]. They are the primary entry point for lymphocytes from the blood.

Q: The ureter is lined by which type of epithelium?

Transitional. **Explanation:** The correct answer is **Transitional epithelium** (also known as **Urothelium**). **Why Transitional Epithelium is Correct:** The urinary tract, from the renal pelvis to the proximal part of the urethra (including the ureter and urinary bladder), is lined by transitional epithelium [1]. This specialized stratified epithelium is designed for two primary functions: 1. **Distensibility:** The cells can glide over one another, changing from cuboidal/columnar in a relaxed state to flattened/squamous when stretched, allowing the ureter to accommodate urine flow. 2. **Impermeability:** The apical "umbrella cells" have thickened plaques (uroplakins) that form a tight osmotic barrier, preventing the reabsorption of toxic urine components back into the blood. **Analysis of Incorrect Options:** * **A. Stratified squamous:** Found in areas subject to mechanical friction (e.g., esophagus, skin, vagina). It provides protection but lacks the distensibility required by the urinary system. * **B. Cuboidal:** Simple cuboidal epithelium is typically found in secretory or absorptive structures like the renal tubules or thyroid follicles. * **C. Ciliated columnar:** Found in the respiratory tract (conducting zone) and fallopian tubes to move mucus or ova [2]. It does not provide the protective barrier needed against urine. **NEET-PG High-Yield Pearls:** * **Umbrella Cells:** The topmost layer of the urothelium consists of large, dome-shaped cells that are often binucleated. * **Histological Layers:** The ureter consists of Mucosa (Urothelium + Lamina propria), Muscularis (Inner longitudinal, Outer circular—*opposite to the GIT*), and Adventitia. * **Distal Ureter Exception:** In the lower third of the ureter, an additional **outer longitudinal** muscle layer is added.

Q: In the intra-epithelial region of the mucosa of the intestine, what is the predominant cell population?

T-cells. ### Explanation The intestinal mucosa is a critical component of the **Gut-Associated Lymphoid Tissue (GALT)**. To answer this question, it is essential to distinguish between the two primary compartments of the mucosal immune system: the **Intra-epithelial layer** and the **Lamina Propria**. **1. Why T-cells are the Correct Answer:** The intra-epithelial region (situated between the columnar epithelial cells) is predominantly populated by **Intraepithelial Lymphocytes (IELs)** [1]. Over 90% of these IELs are **T-cells**. * In the small intestine, the majority are **CD8+ T-cells** (cytotoxic), which serve as the first line of defense against intracellular pathogens and help maintain epithelial integrity [1]. * A significant proportion of these cells express the **gamma-delta ($\gamma\delta$) TCR**, unlike the alpha-beta ($\alpha\beta$) TCR found in systemic circulation. **2. Why the Other Options are Incorrect:** * **B cells & Plasma cells:** While these are abundant in the GALT, they are primarily located in the **Lamina Propria** (the connective tissue layer beneath the epithelium) and in organized follicles like **Peyer’s patches** [1]. Plasma cells here are responsible for secreting **dimeric IgA**. * **Basophils:** These are granulocytes primarily found in the blood. While mast cells (similar to basophils) are found in the GI tract, they reside in the lamina propria and submucosa, not the intra-epithelial layer. **3. Clinical Pearls & High-Yield Facts:** * **IEL Count:** In a healthy small intestine, there are usually < 20–25 IELs per 100 epithelial cells. * **Celiac Disease:** A hallmark histological finding in Celiac disease is **increased IELs** (lymphocytosis), specifically in the villus tips. * **IgA:** Remember that **Secretory IgA** is the most abundant immunoglobulin in the intestinal lumen, but the cells producing it (Plasma cells) stay in the Lamina Propria [1].

Question 1

In which of the following organs are 'peg cells' characteristically seen?

Accepted Answer

Fallopian tubes

Answer

Vagina

Answer

Vulva

Answer

Ovary

Question 2

The cartilage of A is:

Accepted Answer

Elastic

Answer

Fibrous

Answer

White fibro-cartilage

Answer

Hyaline

Question 3

After maturation in the thymus and release into the circulation, T lymphocytes preferentially migrate to which of the following sites?

Accepted Answer

Paracortex of lymph nodes

Answer

Cortical lymphoid nodules of lymph nodes

Answer

Hilum of lymph nodes

Answer

Lymphoid nodules of the tonsils

Question 4

What is the epithelial lining of the vagina?

Accepted Answer

Stratified squamous non-keratinised

Answer

Stratified squamous keratinised

Answer

Columnar

Answer

Cuboidal

Question 5

The ureter is lined by which type of epithelium?

Accepted Answer

Transitional

Answer

Stratified squamous

Answer

Cuboidal

Answer

Ciliated columnar

Question 6

What type of epithelium lines the proximal convoluted tubule (PCT)?

Accepted Answer

Cuboidal Epithelium

Answer

Simple Squamous

Answer

Stratified Squamous

Answer

Columnar Epithelium

Question 7

Which of the following is true about the stratum lucidum?

Accepted Answer

Sandwiched between the stratum corneum and stratum granulosum

Answer

Sandwiched between the stratum spinosum and stratum granulosum

Answer

Contains hair follicles

Answer

Also known as the prickle cell layer

Question 8

What is the epithelial lining of the glottis/true vocal cords?

Accepted Answer

Stratified squamous non-keratinized

Answer

Stratified squamous keratinized

Answer

Ciliated columnar

Answer

Non-ciliated columnar

Question 9

In the intra-epithelial region of the mucosa of the intestine, what is the predominant cell population?

Accepted Answer

T-cells

Answer

B cell

Answer

Plasma cells

Answer

Basophils

Question 10

Which kidney epithelium has the most mitochondria per cell?

Accepted Answer

Proximal convoluted tubule

Answer

Collecting duct

Answer

Urothelium

Answer

Distal convoluted tubule

Microscopic Anatomy — MCQs

Microscopic Anatomy — MCQs

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