Histology — MCQs
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Hassall's corpuscles are found in?
Elastic fibers of tunica media are secreted by
Lining epithelium of vagina is
The nasopharynx is primarily lined by which type of epithelium?
T cells in lymph node are present in:
Type of collagen found in space of Disse in liver is -
What is the approximate number of cones in the human retina?
What is the approximate ratio of connective tissue to smooth muscle in the cervix?
Which type of collagen is primarily responsible for forming the basement membrane sheets?
Identify the type of connective tissue present in the image.
Histology Indian Medical PG Practice Questions and MCQs
Question 451: Hassall's corpuscles are found in?
- A. Lymph nodes
- B. Spleen
- C. Liver
- D. Thymus (Correct Answer)
Explanation: ***Thymus*** - **Hassall's corpuscles**, also known as thymic corpuscles, are unique structures found in the **medulla of the thymus**. - They are composed of concentrically arranged epithelial reticular cells and play a role in **T-cell education** and the development of **regulatory T cells** [2]. *Lymph nodes* - Lymph nodes are secondary lymphoid organs that filter lymph and house **B cells and T cells**, but they do not contain Hassall's corpuscles [1]. - They are characterized by distinct cortical and medullary regions, with germinal centers in the cortex. *Spleen* - The spleen is a secondary lymphoid organ involved in **filtering blood**, removing old red blood cells, and mounting immune responses [1]. - Its parenchyma is divided into **red pulp and white pulp**, but it does not contain Hassall's corpuscles. *Liver* - The liver is primarily involved in **metabolism**, detoxification, and bile production. - It is not a primary lymphoid organ and does not contain structures like Hassall's corpuscles [2].
Question 452: Elastic fibers of tunica media are secreted by
- A. Endothelium
- B. Smooth muscle (Correct Answer)
- C. External lamina
- D. Fibroblast
Explanation: Correct: Smooth muscle - Smooth muscle cells within the tunica media are primarily responsible for synthesizing and secreting elastic fibers along with collagen and proteoglycans [1] - This extracellular matrix provides elasticity and structural integrity to blood vessels, allowing them to stretch and recoil with blood flow [1] - In elastic arteries (like the aorta), smooth muscle cells produce fenestrated elastic membranes that are characteristic of the tunica media Incorrect: Endothelium - Endothelial cells form the innermost lining of blood vessels (tunica intima) and are involved in regulating vascular tone, blood clotting, and inflammation [1] - They do not typically secrete the bulk of elastic fibers found in the tunica media Incorrect: External lamina - The external lamina (or external basal lamina) is an extracellular matrix layer, not a cellular component that secretes elastic fibers - It is actually secreted by the smooth muscle cells themselves and serves as structural support around individual muscle cells Incorrect: Fibroblast - Fibroblasts are connective tissue cells that primarily produce collagen and other extracellular matrix components in many tissues - While they contribute to the tunica adventitia (outermost layer), the tunica media's elastic fibers are primarily produced by smooth muscle cells [1]
Question 453: 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 454: 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].
Question 455: T cells in lymph node are present in:
- A. Paracortical area (Correct Answer)
- B. Mantle layer
- C. Medullary cords
- D. Cortical follicles
Explanation: ***Paracortical area*** - The **paracortical area** contains a high concentration of **T cells**, particularly activated T cells in response to antigenic stimulation [1]. - It plays a crucial role in **immune responses**, bridging the cortex and medulla of the lymph node [1]. *Mantle layer* - The **mantle layer** surrounds the follicles and primarily consists of **B cells**, not T cells. - It is involved in the initial immune response but does not contain a significant number of T lymphocytes. *Medullary cords* - **Medullary cords** mainly contain **plasma cells** and macrophages, with very few T cells present. - Their primary function is the secretion of antibodies rather than T cell activation or response. *Cortical follicles* - **Cortical follicles** are primarily sites for **B cell activation and proliferation**. - While they may have some T cells at their periphery, the majority of T cells are located in the paracortical area.
Question 456: Type of collagen found in space of Disse in liver is -
- A. Collagen I & II
- B. Collagen III & IV (Correct Answer)
- C. Collagen II
- D. Collagen II & V
Explanation: ***Collagen III & IV*** - The **space of Disse** in the liver contains a delicate extracellular matrix predominantly composed of **collagen type III (reticular fibers)**, which provides structural support, and **collagen type IV**, a major component of basement membranes. - This specific collagen composition is crucial for regulating the exchange of solutes between **sinusoidal blood** and **hepatocytes**, as well as for the functional integrity of the liver [1]. *Collagen I & II* - **Collagen type I** is the most abundant collagen in the human body, found in connective tissues like **bone, skin, tendons, and ligaments**, but is not primary in the space of Disse. - **Collagen type II** is characteristic of **hyaline cartilage** and vitreous humor, and is not a significant component of the liver's extracellular matrix in the space of Disse. *Collagen II* - As mentioned, **collagen type II** is primarily found in **cartilage** and vitreous humor, which are distinct from the architectural requirements of the liver sinusoidal space. - Its presence in the space of Disse would not provide the necessary structural flexibility and support for the metabolic functions of the liver. *Collagen II & V* - While **collagen type V** is a minor fibrillar collagen that associates with collagen type I in many tissues, it is not a primary component of the space of Disse. - **Collagen type II** is, again, largely confined to cartilaginous structures, making this an unlikely combination for the liver microenvironment.
Question 457: What is the approximate number of cones in the human retina?
- A. Approximately 3-5 million cones (Correct Answer)
- B. Approximately 25-50 million cones
- C. Approximately 50-100 million cones
- D. Approximately 10-20 million cones
Explanation: Approximately 3-5 million cones - The human retina contains roughly **4.5 million cones**, concentrated in the **fovea**, which is responsible for **high-acuity vision** and color perception [1]. - Cones are light-sensitive cells that detect **fine details** and are essential for vision in **bright light conditions** [1]. *Approximately 10-20 million cones* - This range is significantly higher than the actual number of cones found in the human retina. - While there are millions of photoreceptors, the *majority are rods*, not cones [1]. *Approximately 25-50 million cones* - This figure vastly *overestimates* the number of cones in the human eye. - The total number of photoreceptor cells (rods and cones combined) in the retina typically ranges from **100-125 million** [1]. *Approximately 50-100 million cones* - This range is incorrect as it refers more closely to the *total number of rods* in the human retina, which is about **90-120 million** [1]. - Cones constitute a much smaller proportion of the total photoreceptor population [1].
Question 458: What is the approximate ratio of connective tissue to smooth muscle in the cervix?
- A. 2:1
- B. 5:1
- C. 15:1
- D. Approximately 8:1 (Correct Answer)
Explanation: ***Approximately 8:1*** - The **cervix** is predominantly composed of **fibrous connective tissue**, which provides its structural integrity and rigidity [1]. - This high ratio of **collagenous connective tissue** to smooth muscle is crucial for maintaining pregnancy and undergoing significant remodeling during parturition [1]. - The approximate ratio is **8:1 to 10:1**, with connective tissue forming about 85-90% of cervical tissue [1]. *2:1* - This ratio would imply a significantly higher proportion of **smooth muscle** (33%), making the cervix much more muscular and less fibrous than it actually is. - Such a composition would compromise the cervical function of maintaining a **closed uterine orifice** during pregnancy. *5:1* - While higher than 2:1, this ratio still underestimates the true dominance of **connective tissue** in the cervical structure. - The **cervix's mechanical properties**, including its ability to resist stretching, are primarily due to its abundant collagen content. *15:1* - This ratio overestimates the proportion of connective tissue, suggesting less than 7% smooth muscle. - While the cervix is indeed fibrous, it does contain a modest amount of **smooth muscle** (10-15%) particularly in the internal os region, making this ratio too extreme [1].
Question 459: Which type of collagen is primarily responsible for forming the basement membrane sheets?
- A. Type I
- B. Type II
- C. Type IV (Correct Answer)
- D. Type VI
Explanation: ***Type IV*** - **Type IV collagen** is unique as it forms a **two-dimensional network** that constitutes the structural foundation of **basement membranes**. - Its structure, with **non-fibrillar domains**, allows for assembly into sheets rather than fibrils, providing essential support and filtration properties. *Type I* - **Type I collagen** is the most abundant type in the human body, providing **tensile strength** to tissues like **skin, bone, tendons**, and ligaments. - It forms **thick, striated fibrils** and does not primarily associate with basement membranes [1]. *Type II* - **Type II collagen** is the main collagen found in **cartilage**, providing **resilience and shock absorption**. - It forms thin fibrils within the cartilage matrix and is not a component of basement membranes. *Type VI* - **Type VI collagen** is a minor fibrillar collagen that associates with **interstitial connective tissues**, often forming a **microfibrillar network**. - It links cells to the surrounding matrix and is not a primary component of basement membrane sheets.
Question 460: Identify the type of connective tissue present in the image.
- A. Loose and irregular
- B. Specialized
- C. Dense irregular (Correct Answer)
- D. Dense regular
Explanation: ***Dense irregular*** - The image shows **densely packed collagen fibers** arranged in an **irregular, haphazard fashion**, characteristic of dense irregular connective tissue. - This type of tissue provides **strength** and resistance to stress from multiple directions, found in the **dermis of the skin** and organ capsules. *Loose and irregular* - **Loose connective tissue** would show more ground substance and fewer, loosely arranged fibers, whereas this image displays high fiber density. - While it is "irregular" in fiber arrangement, the density of fibers rules out the "loose" classification. *Specialized* - **Specialized connective tissues** include cartilage, bone, blood, and adipose tissue, which have distinct cellular and extracellular matrix components not seen here. - This tissue lacks the specific cellular and matrix characteristics that would classify it as specialized (e.g., chondrocytes in lacunae, osteocytes, blood cells). *Dense regular* - **Dense regular connective tissue** features collagen fibers arranged in parallel bundles, providing strength in one direction. - Examples include **tendons and ligaments**, which are structurally organized in an orderly, aligned manner, unlike the displayed irregular arrangement.
Practice by Chapter
Basic Tissue Types
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Cell Biology and Organelles
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Epithelial Tissue
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Connective Tissue
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Muscular Tissue
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Nervous Tissue
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Cardiovascular System Histology
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Lymphoid Organs and Immune System
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Endocrine System Histology
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Respiratory System Histology
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Digestive System Histology
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Urinary and Reproductive System Histology
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