Histology Practice Questions

Q: Hassall's corpuscles are observed in which anatomical structure?

Thymus. **Explanation:** **Hassall’s corpuscles** (also known as thymic corpuscles) are the pathognomonic histological feature of the **Thymus**. They are located exclusively in the **medulla** of the thymic lobules. [1] Structurally, they consist of concentric layers of flattened epithelial reticular cells that have undergone keratinization and sometimes calcification. Their primary function is the production of cytokines (like TSLP) that aid in the development of regulatory T-cells. **Analysis of Incorrect Options:** * **B. Spleen:** Characterized by White Pulp (containing PALS and Malpighian corpuscles) and Red Pulp (containing splenic cords and sinusoids). [2] It does not contain Hassall’s corpuscles. * **C. Lymph Node:** Distinguished by an outer cortex containing lymphoid follicles (B-cells) and an inner medulla with medullary cords and sinuses. [2] * **D. Appendix:** A part of the GALT (Gut-Associated Lymphoid Tissue), it is identified by a continuous ring of lymphoid follicles in the submucosa and the absence of a distinct medulla. **High-Yield Clinical Pearls for NEET-PG:** * **Location:** Hassall's corpuscles are found only in the **Medulla**, never the cortex. * **Origin:** They are derived from the **3rd pharyngeal pouch** (endoderm). * **Ageing:** As the thymus undergoes "age involution" post-puberty, the number of Hassall’s corpuscles may actually increase or become more prominent as the lymphoid tissue is replaced by fat. * **DiGeorge Syndrome:** Characterized by the absence of the thymus (and Hassall’s corpuscles) due to the failure of the 3rd and 4th pharyngeal pouches to develop.

Q: Hyaline cartilage is found in all of the following locations except?

External Ear. The correct answer is **D. External Ear**. **1. Why External Ear is the Correct Answer:** The external ear (pinna) is composed of **Elastic Cartilage**, not hyaline cartilage. Elastic cartilage is characterized by a dense network of branching elastic fibers (elastin) within its matrix, providing the flexibility and structural resilience required for the ear to maintain its shape after being bent. **2. Analysis of Incorrect Options:** * **Costal Cartilage:** These connect the ribs to the sternum and are classic examples of hyaline cartilage. They provide semi-rigid support and allow for chest wall expansion. * **Thyroid Cartilage:** Most of the laryngeal cartilages (Thyroid, Cricoid, and the base of Arytenoids) are **Hyaline**. Note: The Epiglottis and the tips of the Arytenoids are Elastic. * **Foetal Skeleton:** Hyaline cartilage serves as the temporary "model" for the embryonic skeleton before it undergoes endochondral ossification to become bone [2]. **3. High-Yield Clinical Pearls for NEET-PG:** * **Hyaline Cartilage (Most Common):** Found in Articular surfaces (except TMJ), Tracheal rings, Bronchi, Larynx (Thyroid/Cricoid), and Nasal septum. It contains Type II Collagen [1]. * **Elastic Cartilage (The "E" Rule):** Found in **E**xternal ear, **E**ustachian tube, and **E**piglottis. * **Fibrocartilage (Strongest):** Found in Intervertebral discs, Pubic symphysis, and Menisci. It contains Type I Collagen. * **Calcification:** Hyaline and Fibrocartilage can calcify with age; Elastic cartilage **never** calcifies. * **Articular Cartilage:** A unique type of hyaline cartilage that lacks a perichondrium [1].

Q: Which of the following structures is lined by urothelium?

Membranous urethra. The lining of the urinary tract undergoes a transition from **urothelium** (transitional epithelium) to **stratified squamous epithelium** as it approaches the external environment. **Why Option D is the Correct Answer:** The **membranous urethra** is the shortest and least dilatable part of the male urethra. It is lined by **pseudostratified or stratified columnar epithelium**, not urothelium. The question likely follows the standard anatomical convention that urothelium ends at the level of the prostatic urethra. Beyond the prostatic urethra, the lining transitions to columnar and eventually stratified squamous epithelium in the distal parts. **Analysis of Incorrect Options:** * **A. Ureters:** These are classic examples of structures lined by **urothelium**. The thick epithelial layer allows for stretching and protects the underlying tissue from the toxic effects of urine. * **B. Minor Calyx:** The entire collecting system, starting from the **renal calyces** (minor and major) down to the renal pelvis, is lined by **urothelium**. * **C. Urinary Bladder:** The bladder is the primary reservoir lined by **urothelium** [1]. Its specialized "umbrella cells" allow the bladder to expand significantly without losing its barrier function. In the interior of the bladder, the mucosa is lined by transitional epithelium with no glands [2]. **High-Yield NEET-PG Pearls:** 1. **Urothelium Extent:** It lines the urinary tract from the renal calyces to the **prostatic urethra** in males and the **proximal urethra** in females. 2. **Histology:** Urothelium is characterized by **umbrella cells** (surface cells) that contain **uroplakin** plaques, making the barrier impermeable to water and salts [1]. 3. **Urethral Lining Transition:** * Prostatic: Urothelium. * Membranous/Bulbar: Pseudostratified/Stratified Columnar. * Navicular Fossa: Stratified Squamous (non-keratinized).

Q: Which of the following glands does NOT contain myoepithelial cells?

Sebaceous glands. The presence of **myoepithelial cells** is a characteristic feature of glands that require active contraction to expel their secretions. These cells are located between the basement membrane and the secretory epithelial cells. **Why Sebaceous Glands are the Correct Answer:** Sebaceous glands are **holocrine glands**, meaning the entire cell disintegrates to release its lipid-rich product (sebum). Because the secretion is released through the accumulation of internal pressure and cell breakdown rather than active contraction, **myoepithelial cells are absent**. Instead, sebum is pushed out by the continuous production of new cells at the base of the gland. **Analysis of Incorrect Options:** * **Mammary Glands:** These are modified apocrine glands. Myoepithelial cells surround the alveoli and contract in response to **oxytocin** (the milk-ejection reflex). * **Salivary Glands:** Both serous and mucous acini possess myoepithelial cells (often called "basket cells") to facilitate the flow of saliva into the ductal system. * **Sweat Glands:** Both eccrine and apocrine sweat glands contain myoepithelial cells. In eccrine glands, they help rapidly expel sweat during thermoregulation. **High-Yield Clinical Pearls for NEET-PG:** * **Origin:** Myoepithelial cells are **ectodermal** in origin, despite having contractile properties similar to smooth muscle (which is mesodermal). * **Markers:** They can be identified histologically using markers like **p63, SMA (Smooth Muscle Actin), and S-100**. * **Tumor Pathology:** The presence of myoepithelial cells is often a key diagnostic feature in distinguishing benign breast lesions (where they are preserved) from invasive carcinoma (where they are typically lost).

Q: Which term describes a centromere located near the end of a chromosome?

Acrocentric. **Explanation:** Chromosomes are classified based on the position of the **centromere**, which divides the chromosome into a short arm (**p arm**) and a long arm (**q arm**). **1. Why Acrocentric is correct:** In **acrocentric** chromosomes, the centromere is located **near the end**. This results in one arm being extremely short, often terminating in "satellites" (stalk-like structures containing ribosomal RNA genes). In humans, chromosomes **13, 14, 15, 21, and 22** are acrocentric. **2. Analysis of Incorrect Options:** * **Metacentric:** The centromere is located in the **middle**, resulting in two arms of approximately equal length (e.g., Chromosome 1). * **Submetacentric:** The centromere is slightly off-center, creating a distinct short arm (p) and a long arm (q). * **Telocentric:** The centromere is at the **very tip (telomere)**, resulting in only one visible arm. **Note:** Telocentric chromosomes do not occur naturally in humans but are found in other species like mice. **3. High-Yield Clinical Pearls for NEET-PG:** * **Robertsonian Translocation:** This unique type of translocation occurs **only between acrocentric chromosomes**. The long arms fuse at the centromere, and the short arms are lost. This is a significant cause of familial Down Syndrome (Trisomy 21). * **Nucleolar Organizer Regions (NORs):** In acrocentric chromosomes, the satellites contain NORs, which are essential for the formation of the nucleolus. * **Mnemonic for Human Acrocentrics:** "D and G group chromosomes" (13-15 and 21-22).

Q: Capillary invasion of corpus luteum begins?

2 days after ovulation. The formation of the **Corpus Luteum** is a dynamic process involving the transformation of the ruptured Graafian follicle. Following ovulation (Day 14 of a typical cycle), the basement membrane between the granulosa and theca cells breaks down. **Why Option B is correct:** The process of **luteinization** begins immediately after ovulation, but significant **vascularization (capillary invasion)** specifically occurs on **Day 2 after ovulation** (Day 16 of the cycle). Angiogenic factors (like VEGF) stimulate the vessels from the theca interna to sprout and invade the granulosa layer, which was previously avascular. This rapid vascularization is essential to deliver cholesterol to the lutein cells for the massive production of progesterone. **Analysis of Incorrect Options:** * **Option A (1 day after):** On the first day, the follicle collapses and forms the *corpus hemorrhagicum*. While the basement membrane begins to disrupt, the organized invasion of capillaries is not yet established. * **Option C & D (3 & 4 days after):** By this time, the capillary network is already well-established. The peak vascularity and peak progesterone production usually occur around Day 7–8 post-ovulation (Day 21–22 of the cycle). **NEET-PG High-Yield Pearls:** * **Granulosa Lutein Cells:** Derived from granulosa cells; produce Progesterone and Inhibin A. * **Theca Lutein Cells:** Derived from theca interna; produce Estrogen and Androgens. * **Life Span:** If fertilization does not occur, the corpus luteum degenerates into the **Corpus Albicans** after approximately 14 days due to a drop in LH. * **HCG Role:** If pregnancy occurs, HCG (produced by syncytiotrophoblast) rescues the corpus luteum to maintain progesterone levels until the placenta takes over (around 8–10 weeks). [1]

Q: Which one of the following cell types is found in the least numbers in the pituitary gland?

Thyrotrophs. The anterior pituitary (adenohypophysis) contains five distinct cell types that secrete specific hormones. These cells are distributed in varying proportions, which is a high-yield topic for NEET-PG. ### **Why Thyrotrophs are the Correct Answer** **Thyrotrophs** are the least abundant cell type in the anterior pituitary, accounting for only **3–5%** of the total cell population. They secrete Thyroid-Stimulating Hormone (TSH). Despite their small number, they are highly efficient in maintaining systemic metabolic homeostasis. ### **Analysis of Incorrect Options** * **Lactotrophs (Option A):** These make up about **15–25%** of the gland. They secrete Prolactin. Their numbers can significantly increase (hyperplasia) during pregnancy and lactation due to estrogen stimulation. * **Gonadotrophs (Option C):** These constitute approximately **10–15%** of the cells. They are unique because a single cell type typically secretes two different hormones: LH and FSH. * **Corticotrophs (Option D):** These make up about **15–20%** of the cells and secrete ACTH. They are usually the first cells to recover after pituitary suppression. *(Note: **Somatotrophs**, which secrete Growth Hormone, are the **most abundant** cell type, comprising about 40–50% of the gland.)* ### **High-Yield NEET-PG Pearls** 1. **Abundance Hierarchy:** Somatotrophs (50%) > Lactotrophs (20%) > Corticotrophs (15%) > Gonadotrophs (10%) > **Thyrotrophs (5%)**. 2. **Staining Characteristics:** * **Acidophils:** Somatotrophs and Lactotrophs (Mnemonic: **GPA** – **G**rowth hormone, **P**rolactin are **A**cidophils). * **Basophils:** Corticotrophs, Thyrotrophs, and Gonadotrophs (Mnemonic: **B-FLAT** – **B**asophils are **F**SH, **L**H, **A**CTH, **T**SH). 3. **Location:** Thyrotrophs are primarily located in the **anteromedial** portion of the pituitary.

Q: Uterus, before menarche, is lined by which type of epithelium?

Ciliated columnar epithelium. The lining of the uterus (endometrium) undergoes significant histological changes based on age and hormonal status. **1. Why Ciliated Columnar Epithelium is correct:** Before menarche, the endometrium is relatively thin and inactive. It is lined by a **simple ciliated columnar epithelium** [1]. These cilia are essential during early development and prepubertal stages. After menarche, under the influence of estrogen and progesterone, the epithelium remains columnar but the proportion of ciliated cells fluctuates; they are most prominent during the proliferative phase and decrease after ovulation [2]. **2. Analysis of Incorrect Options:** * **B & C (Stratified Squamous):** This epithelium is designed for protection against mechanical stress. Non-keratinized stratified squamous epithelium lines the **vagina** and the **ectocervix**. Keratinized epithelium is found on the skin. The presence of squamous cells inside the uterine cavity is pathological (e.g., squamous metaplasia). * **D (Cuboidal Epithelium):** While some inactive or atrophic endometrial glands may appear low-columnar or cuboidal (especially in post-menopausal states), the surface lining is characteristically columnar. **3. High-Yield Clinical Pearls for NEET-PG:** * **Fallopian Tube:** Also lined by ciliated columnar epithelium (highest concentration of cilia in the infundibulum and ampulla to facilitate ovum transport). * **Endocervix:** Lined by simple columnar epithelium (mucin-secreting) [1]. * **Transformation Zone:** The junction where the simple columnar epithelium of the endocervix meets the stratified squamous epithelium of the ectocervix; this is the most common site for cervical cancer. * **Post-menopause:** The endometrium becomes atrophic, and the epithelium may lose its cilia and become low columnar.

Q: Fibromuscular stroma is present in which of the following organs?

Prostate. The **prostate gland** is unique because it is not purely glandular; it is a **fibromuscular organ**. Its stroma consists of a dense mixture of smooth muscle fibers and collagenous connective tissue. ### Why Prostate is Correct: The prostate is composed of approximately **70% glandular tissue** and **30% fibromuscular stroma**. This stroma is continuous with the capsule and contains smooth muscle fibers that contract during ejaculation to squeeze prostatic secretions into the prostatic urethra. A key anatomical landmark is the **Anterior Fibromuscular Stroma (AFMS)**, which forms the anterior surface of the prostate and is devoid of glandular elements. ### Why Other Options are Incorrect: * **Testis:** The structural framework consists of the *tunica albuginea* (dense connective tissue), but the parenchyma is dominated by seminiferous tubules, not a specialized fibromuscular stroma. * **Liver:** The liver is covered by *Glisson’s capsule*. Its internal framework consists of a delicate reticular fiber network (Type III collagen) to support hepatocytes, lacking a significant smooth muscle component. * **Urinary Bladder:** While the bladder wall contains thick smooth muscle (the *detrusor muscle*), it is classified as a hollow muscular organ rather than a gland with a fibromuscular stroma [1]. ### High-Yield Clinical Pearls for NEET-PG: * **BPH (Benign Prostatic Hyperplasia):** Primarily involves the **Transition Zone**. The stromal component (smooth muscle) is the target for **Alpha-1 blockers** (e.g., Tamsulosin), which relax the stroma to improve urine flow. * **Prostate Cancer:** Most commonly arises in the **Peripheral Zone**. * **Histology Tip:** On an H&E stain, the prostatic stroma appears characteristically pink (eosinophilic) due to the high density of smooth muscle.

Q: C cells are present in which gland?

Thyroid gland. C cells, also known as **Parafollicular cells**, are neuroendocrine cells located within the connective tissue between the thyroid follicles or embedded in the follicular lining. Their primary function is to secrete **Calcitonin**, a hormone that lowers blood calcium levels by inhibiting osteoclast activity and increasing renal calcium excretion [1]. **2. Why Other Options are Incorrect:** * **Parathyroid Gland:** This gland contains **Chief cells** (which secrete Parathyroid Hormone/PTH) and **Oxyphil cells** [2]. PTH is the functional antagonist to Calcitonin. * **Pituitary Gland:** The anterior lobe contains acidophils (Somatotropes, Lactotropes) and basophils (Corticotropes, Thyrotropes, Gonadotropes), while the posterior lobe contains pituicytes and axonal terminals. * **Thymus:** This lymphoid organ contains T-lymphocytes (thymocytes) and **Hassall’s corpuscles** (epithelial reticular cells), but no C cells. **3. High-Yield Clinical Pearls for NEET-PG:** * **Embryology:** C cells are derived from the **Ultimobranchial body** (ventral wing of the 4th/5th pharyngeal pouch), which originates from the **Neural Crest**. * **Tumor Marker:** C cells are the cells of origin for **Medullary Carcinoma of the Thyroid (MTC)**. Serum Calcitonin levels are used as a specific tumor marker for diagnosis and follow-up [3]. * **MEN Syndrome:** Medullary thyroid carcinoma is a key component of **MEN 2A and 2B** syndromes [3]. * **Staining:** C cells can be identified using immunohistochemistry for **Chromogranin** or **Calcitonin**.

Question 1

Hassall's corpuscles are observed in which anatomical structure?

Accepted Answer

Thymus

Answer

Spleen

Answer

Lymph node

Answer

Appendix

Question 2

Hyaline cartilage is found in all of the following locations except?

Accepted Answer

External Ear

Answer

Costal Cartilage

Answer

Thyroid Cartilage

Answer

Foetal Skeleton

Question 3

Which of the following structures is lined by urothelium?

Accepted Answer

Membranous urethra

Answer

Ureters

Answer

Minor calyx

Answer

Urinary bladder

Question 4

Which of the following glands does NOT contain myoepithelial cells?

Accepted Answer

Sebaceous glands

Answer

Mammary glands

Answer

Salivary glands

Answer

Sweat glands

Question 5

Which term describes a centromere located near the end of a chromosome?

Accepted Answer

Acrocentric

Answer

Metacentric

Answer

Submetacentric

Answer

Telocentric

Question 6

Capillary invasion of corpus luteum begins?

Accepted Answer

2 days after ovulation

Answer

One day after ovulation

Answer

3 days after ovulation

Answer

4 days after ovulation

Question 7

Which one of the following cell types is found in the least numbers in the pituitary gland?

Accepted Answer

Thyrotrophs

Answer

Lactotrophs

Answer

Gonadotrophs

Answer

Corticotrophs

Question 8

Uterus, before menarche, is lined by which type of epithelium?

Accepted Answer

Ciliated columnar epithelium

Answer

Stratified squamous non-keratinized epithelium

Answer

Stratified squamous keratinized epithelium

Answer

Cuboidal epithelium

Question 9

Fibromuscular stroma is present in which of the following organs?

Accepted Answer

Prostate

Answer

Testis

Answer

Liver

Answer

Urinary bladder

Question 10

C cells are present in which gland?

Accepted Answer

Thyroid gland

Answer

Parathyroid gland

Answer

Pituitary gland

Answer

Thymus

Histology — MCQs

Histology — MCQs

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