Urinary and Reproductive System Histology — MCQs
Renin is secreted from which of the following?
Lining epithelium of vagina is
Podocytes are seen in -
What happens to the concentration of inulin as fluid passes through the Proximal Convoluted Tubule (PCT)?
Loss of foot process is classical in case of?
The lower two thirds of the following hematoxylin and eosin stained specimen is similar in appearance to which of the following structures?
Biopsy of the exposed surface of the palatine tonsil reveals which type of tissue?
Epithelial lining of the urinary bladder is?
Identify the structure marked in the image of cardiac myocyte. (AIIMS Nov 2018)
The nasopharynx is primarily lined by which type of epithelium?
Urinary and Reproductive System Histology Indian Medical PG Practice Questions and MCQs
Question 1: Renin is secreted from which of the following?
- A. JG cells (Correct Answer)
- B. Mesangial cells
- C. Macula densa cells
- D. Lacis cells
Explanation: ***JG cells*** - **Juxtaglomerular (JG) cells** are specialized smooth muscle cells located in the **afferent arteriole** of the kidney glomerulus. - They synthesize, store, and release **renin** in response to decreased renal perfusion pressure, sympathetic stimulation, or decreased sodium delivery to the macula densa. *Mesangial cells* - **Mesangial cells** are connective tissue cells located within the glomerulus, between the glomerular capillaries. - They provide structural support for the glomerular capillaries and play a role in regulating glomerular filtration, but they **do not secrete renin**. *Macula densa cells* - **Macula densa cells** are specialized epithelial cells in the distal convoluted tubule that sense **sodium chloride concentration** in the filtrate. - While they are part of the juxtaglomerular apparatus and influence renin release, they **do not directly secrete renin** themselves; instead, they signal JG cells. *Lacis cells* - **Lacis cells** (also known as extraglomerular mesangial cells) are located in the angle between the afferent and efferent arterioles, adjacent to the macula densa and JG cells. - Their exact function is not fully understood, but they are thought to facilitate communication within the **juxtaglomerular apparatus** and provide structural support, not renin secretion.
Question 2: Lining epithelium of vagina is
- A. Squamous epithelium (Correct Answer)
- B. Columnar epithelium
- C. Transitional epithelium
- D. Secretory epithelium
Explanation: Squamous epithelium * The vagina is lined by stratified squamous non-keratinized epithelium [1], providing a protective barrier against friction and pathogens. * This type of epithelium is well-suited for areas subject to significant mechanical stress, such as during intercourse and childbirth. Columnar epithelium * Columnar epithelium [2] is typically found in areas specialized for secretion and absorption, such as the gastrointestinal tract and glandular linings. * It would not offer the necessary protective qualities for the vaginal environment. Transitional epithelium * Transitional epithelium is a specialized stratified epithelium found in the urinary tract, capable of stretching and distending. * It is not found in the vagina, which requires a more robust, friction-resistant lining. Secretory epithelium * While the cervix has secretory glands, the lining of the vagina itself is not primarily secretory. * The primary role of the vaginal lining is protection, not secretion, and its cells do not typically produce a large amount of substances.
Question 3: Podocytes are seen in -
- A. Bowman's capsule (Correct Answer)
- B. Proximal convoluted tubule
- C. Distal convoluted tubule
- D. Collecting tubule of the kidney
Explanation: **Bowman's capsule** - **Podocytes** are specialized epithelial cells that form the **visceral layer** of Bowman's capsule. They have foot processes (pedicels) that interdigitate to form slit diaphragms, which are crucial for the **filtration barrier** of the glomerulus [1]. - These cells facilitate the selective passage of water and small solutes from the blood into Bowman's space, while preventing the filtration of large proteins and blood cells. *Proximal convoluted tubule* - The **proximal convoluted tubule** is primarily involved in the **reabsorption** of essential nutrients, ions, and water from the filtrate back into the bloodstream [1]. - Its cells are characterized by a **brush border** (microvilli) and numerous mitochondria, indicating high metabolic activity, and are not podocytes [1]. *Distal convoluted tubule* - The **distal convoluted tubule** plays a role in fine-tuning the reabsorption of ions and water, under the influence of hormones like **aldosterone** and **ADH**. - Its cells lack the specialized foot processes and filtration function characteristic of podocytes. *Collecting tubule of the kidney* - The **collecting tubule** (or collecting duct) is involved in regulating water reabsorption and acid-base balance, responding to **ADH** to concentrate urine. - Its epithelial cells are principal cells and intercalated cells, which are different in structure and function from podocytes.
Question 4: What happens to the concentration of inulin as fluid passes through the Proximal Convoluted Tubule (PCT)?
- A. Concentration of inulin increases (Correct Answer)
- B. Concentration of urea remains constant
- C. Concentration of HCO3- increases
- D. Concentration of Na+ decreases
Explanation: ***Concentration of inulin increases*** - Inulin is **freely filtered** at the glomerulus and is neither reabsorbed nor secreted along the renal tubule, making it an excellent marker for **glomerular filtration rate (GFR)**. - As water is reabsorbed from the PCT, the volume of tubular fluid decreases, causing the concentration of **unreabsorbed solutes**, like inulin, to increase. *Concentration of urea remains constant* - Urea is **reabsorbed** along the tubule, though passively; its concentration typically **increases** initially in the PCT due to water reabsorption, but then decreases as some is reabsorbed. - The statement is incorrect because urea concentration changes significantly throughout the nephron, particularly increasing as water is reabsorbed and then decreasing with some reabsorption. *Concentration of HCO3- increases* - The majority (approximately 80-90%) of **bicarbonate (HCO3-)** is reabsorbed in the PCT, primarily through its conversion to CO2 within the tubular lumen and then back to HCO3- intracellularly. - Therefore, the concentration of HCO3- in the tubular fluid actually **decreases** significantly as fluid passes through the PCT. *Concentration of Na+ decreases* - **Sodium (Na+)** is actively reabsorbed along the entire nephron, with about 65-70% reabsorbed in the PCT. - While Na+ is reabsorbed, water follows passively, so its concentration in the tubular fluid remains relatively **iso-osmotic** with plasma, meaning its concentration does not significantly decrease as fluid passes through the PCT, remaining fairly constant.
Question 5: Loss of foot process is classical in case of?
- A. Segmental glomerulosclerosis (Correct Answer)
- B. Diabetic nephropathy (later stages)
- C. Membranous nephropathy
- D. IgA vasculitis
Explanation: ***Segmental glomerulosclerosis*** - Characterized by a **loss of foot processes**, leading to a "focal" or "segmental" pattern of sclerosis on histology [1][2]. - Often presents with **nephrotic syndrome**, including proteinuria and edema, due to damage to the glomeruli [1][3]. *Membranous glomerulitis* - Primarily involves **thickening of the glomerular capillary walls** without the loss of foot processes initially. - It is often associated with **membrane antibodies** and can lead to nephrotic syndrome, but not specifically linked to foot process loss [2]. *Diabetic nephropathy* - Characterized by **nodular glomerulosclerosis** and other microvascular changes, but the loss of foot processes is not a classic feature. - Typically presents with **diffuse glomerular basement membrane thickening** and eventual renal failure. *IgA nephropathy* - Characterized by the deposition of **IgA antibodies** in the mesangial area, leading to hematuria but not directly causing loss of foot processes. - Symptoms often include **recurrent episodes of hematuria** which can be triggered by infection, rather than nephrotic syndrome. **References:** [1] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, pp. 927-928. [2] Cross SS. Underwood's Pathology: A Clinical Approach. 6th ed. Common Clinical Problems From Diseases Of The Urinary And Male Genital Tracts, pp. 530-532. [3] Kumar V, Abbas AK, et al.. Robbins and Cotran Pathologic Basis of Disease. 9th ed. The Kidney, p. 913.
Question 6: The lower two thirds of the following hematoxylin and eosin stained specimen is similar in appearance to which of the following structures?
- A. Articular disk
- B. Pinna
- C. Epiphyseal growth plate
- D. Intervertebral disk (Correct Answer)
Explanation: ***Intervertebral disk*** - The lower two-thirds of the specimen shows **hyaline-like cartilage** that histologically resembles the **transition zone** of the intervertebral disk, where the inner annulus fibrosus transitions from the nucleus pulposus. - While the nucleus pulposus itself is gelatinous and notochordal in origin, the **inner annulus fibrosus** contains fibrocartilage with regions that can appear similar to hyaline cartilage, particularly in the transitional zones. - The specimen's appearance, with **chondrocytes in lacunae** within a relatively homogeneous matrix, matches the cartilaginous components found in intervertebral disk structure. *Articular disk* - Articular disks are composed predominantly of **fibrocartilage**, characterized by **dense parallel collagen fiber bundles** clearly visible in the matrix and chondrocytes arranged in linear rows between collagen bundles. - The homogeneous matrix appearance in the specimen lacks the prominent fibrous architecture typical of articular disks. *Pinna* - The pinna (external ear) is supported by **elastic cartilage**, which contains abundant **elastic fibers** in its extracellular matrix providing flexibility and resilience. - With H&E staining, elastic cartilage would show a more textured matrix, and special stains would demonstrate extensive elastic fiber networks not present in this specimen. *Epiphyseal growth plate* - While the epiphyseal growth plate consists of **hyaline cartilage**, it exhibits highly characteristic **zonal organization**: resting zone, proliferative zone (with columnar arrangement), hypertrophic zone, and zone of calcification. - The specimen lacks the distinct columnar arrangement and zonal stratification that defines an active epiphyseal growth plate.
Question 7: Biopsy of the exposed surface of the palatine tonsil reveals which type of tissue?
- A. Stratified squamous epithelium (Correct Answer)
- B. Simple squamous epithelium
- C. Simple columnar epithelium
- D. Pseudostratified columnar ciliated epithelium
Explanation: The palatine tonsils are part of the **oropharynx**, which is subjected to mechanical abrasion from food and drink. **Stratified squamous epithelium** provides robust protection against such friction and is characteristic of surfaces needing high wear resistance. *Simple squamous epithelium* - This type of epithelium is found in areas where **diffusion** or **filtration** is important, such as the lining of blood vessels (endothelium) and alveoli of the lungs. - It would not provide adequate protection for the exposed surface of the tonsil that is subject to frequent mechanical stress. *Simple columnar epithelium* - Characterized by cells taller than they are wide, often found in the **gastrointestinal tract** for absorption and secretion. - It lacks the multi-layered structure needed for protection against the abrasive forces typical in the oropharynx. *Pseudostratified columnar ciliated epithelium* - This epithelium is primarily found in the **respiratory tract**, where its cilia help move mucus and trapped particles. - While it offers some protection, its primary function is not mechanical resistance, and it is not found on the exposed surfaces of the palatine tonsils.
Question 8: Epithelial lining of the urinary bladder is?
- A. Squamous epithelium
- B. Transitional epithelium (Correct Answer)
- C. Cuboidal epithelium
- D. Columnar epithelium
Explanation: ***Transitional epithelium*** - The urinary bladder is lined by **transitional epithelium**, also known as **urothelium** [1]. - This specialized epithelium can stretch and flatten when the bladder fills with urine, and then contract when it empties, a crucial adaptation for its function. *Squamous epithelium* - **Stratified squamous epithelium** is typically found in areas subject to abrasion, such as the skin, esophagus, and vagina. - It does not possess the unique distensibility required for the urinary bladder's function. *Cuboidal epithelium* - **Cuboidal epithelium** is commonly found in glands and kidney tubules, where it is involved in secretion and absorption. - It is not specialized for the significant stretching and recoiling seen in the urinary bladder. *Columnar epithelium* - **Columnar epithelium** is primarily involved in secretion and absorption and is found in regions like the gastrointestinal tract and some glandular ducts. - It lacks the necessary structural characteristics to accommodate the large volume changes of the urinary bladder.
Question 9: Identify the structure marked in the image of cardiac myocyte. (AIIMS Nov 2018)
- A. Lipofuscin granules (Correct Answer)
- B. Lysosomes
- C. Phagolysosome
- D. Inflammasome
Explanation: ***Lipofuscin granules*** - The image displays electron-dense, irregular structures, characteristic of **lipofuscin granules**, which are wear-and-tear pigments accumulating in aging cardiac myocytes. - They are typically located near the nucleus and appear dark due to their complex lipid-protein composition. *Lysosomes* - Lysosomes are typically smaller, more uniformly shaped, and contain hydrolytic enzymes, which is not clearly depicted. - While involved in cellular waste breakdown, they do not typically accumulate as large, intensely electron-dense, irregular aggregates like those shown. *Phagolysosome* - A phagolysosome forms when a phagosome fuses with a lysosome, containing engulfed material often of foreign or cellular debris origin. - The image does not show evidence of recently engulfed material or the typical morphology of a phagocytic vesicle. *Inflammasome* - An inflammasome is a multi-protein intracellular complex involved in the inflammatory response, not a visibly distinct organelle with this characteristic electron microscopic appearance. - It is a signaling platform, not a storage granule, and would not appear as dense, granular deposits in a routine electron micrograph.
Question 10: The nasopharynx is primarily lined by which type of epithelium?
- A. Stratified squamous keratinized
- B. Ciliated columnar (Correct Answer)
- C. Cuboidal
- D. Stratified squamous nonkeratinized
Explanation: ***Ciliated columnar*** - The **nasopharynx** is lined by **pseudostratified ciliated columnar epithelium** with goblet cells, also known as respiratory epithelium [2]. - This specialized epithelium is crucial for **warming**, **humidifying**, and **filtering** inhaled air before it reaches the lungs [1]. *Stratified squamous nonkeratinized* - This type of epithelium is found in areas subject to **abrasion** and needing protection, such as the **oral cavity**, pharynx (oropharynx and laryngopharynx), and esophagus. - It is not primary in the nasopharynx, which requires ciliary action for particle removal. *Stratified squamous keratinized* - This robust epithelium is characteristic of areas that require significant **protection against friction** and **drying**, such as the **epidermis of the skin**. - It is not found in the nasopharynx due to its lack of flexibility and ciliary function. *Cuboidal* - **Cuboidal epithelium** is typically found in glands and kidney tubules, where its function includes **secretion** and **absorption**. - It lacks the specialized cilia and goblet cells necessary for the respiratory function of the nasopharynx [2].
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