Histology — MCQs
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What are gap junctions composed of?
Reinke's layer is seen in:
The thin limbs of the ansa nephroni are primarily lined by what?
Which of the following statements about the periosteum is false?
Lymphatic follicles are not seen in:
The mucosal lining of the vagina is composed of cells:
Which layer of the epidermis is responsible for its proliferation and turnover?
Biopsy of the exposed surface of the palatine tonsil reveals which type of tissue?
Which type of collagen is most abundant in hyaline cartilage?
Stem cells are typically harvested from all except which?
Histology Indian Medical PG Practice Questions and MCQs
Question 471: What are gap junctions composed of?
- A. Catenins
- B. Cadherins
- C. Connexins (Correct Answer)
- D. Claudin
Explanation: ***Connexins*** - **Gap junctions** are intercellular channels that permit the passage of ions and small molecules between adjacent cells [1], and they are primarily formed by proteins called **connexins** [1]. - Six connexin proteins assemble to form a **connexon**, also known as a hemichannel, which then docks with a connexon from an adjacent cell to create a complete gap junction channel [1]. *Catenins* - **Catenins** are a group of proteins involved in cell adhesion by linking cadherins to the **actin cytoskeleton**. - They are crucial for the stability and function of **adherens junctions**, not gap junctions [2]. *Cadherins* - **Cadherins** are transmembrane proteins that mediate **calcium-dependent cell-cell adhesion** in adherens junctions and desmosomes. - They are responsible for homophilic binding between cells, playing a key role in tissue segregation and morphogenesis, but do not form channels [2]. *Claudin* - **Claudins** are a family of proteins that are essential components of **tight junctions** [2]. - They help to form the primary seal of tight junctions, regulating paracellular permeability and maintaining cell polarity [2].
Question 472: Reinke's layer is seen in:
- A. Vocal cord (Correct Answer)
- B. Tympanic membrane
- C. Cochlea
- D. Reissner's membrane
Explanation: ***Vocal cord*** - **Reinke's space**, also known as Reinke's layer, is the superficial layer of the **lamina propria** of the vocal cord. - This layer is crucial for the **vibration of the vocal folds**, which is essential for sound production. *Tympanic membrane* - The **tympanic membrane**, or eardrum, is a thin membrane that separates the external ear from the middle ear [1]. [2]. - It vibrates in response to **sound waves** and transmits these vibrations to the ossicles, playing a role in hearing, not vocalization [1], [2]. *Cochlea* - The **cochlea** is a spiral-shaped cavity in the inner ear involved in the sense of hearing [2]. - It contains the **organ of Corti**, which converts sound vibrations into nerve impulses but has no connection to vocal cord anatomy [2]. *Reissner's membrane* - **Reissner's membrane** (vestibular membrane) is a thin membrane that separates the scala vestibuli from the scala media within the cochlea. - Its primary function is to maintain the **composition of the endolymph** in the scala media, and it is part of the auditory system, not the larynx.
Question 473: The thin limbs of the ansa nephroni are primarily lined by what?
- A. Cuboidal epithelium
- B. Columnar epithelium
- C. Squamous epithelium (Correct Answer)
- D. Stratified squamous epithelium
Explanation: Squamous epithelium - The thin limbs of the loop of Henle (ansa nephroni) are characterized by their simple, flattened squamous epithelial cells [1]. - This thin lining facilitates efficient passive diffusion of water and solutes, crucial for urine concentration [2]. Columnar - Columnar epithelial cells are typically found in regions involved in secretion and absorption, such as the gastrointestinal tract, not the thin limbs of the ansa nephroni. - Their tall, cylindrical shape is suited for active transport processes rather than passive diffusion. Cuboidal epithelium - Cuboidal epithelium lines the proximal and distal convoluted tubules and the thick ascending limb of the loop of Henle, where active transport of ions and reabsorption of water occur [1]. - These cells have abundant mitochondria to support their metabolic activity, which is not characteristic of the thin limbs. Stratified squamous epithelium - Stratified squamous epithelium is a protective lining found in areas subject to abrasion, such as the skin and mucosa of the mouth and esophagus. - It is not found in the kidney tubules, which are involved in filtration and reabsorption.
Question 474: Which of the following statements about the periosteum is false?
- A. It does not cover the articular surface of the bones
- B. It is pierced by the fibers of Sharpey's
- C. It is highly vascular
- D. It is insensitive to pain (Correct Answer)
Explanation: ***It is insensitive to pain*** - The periosteum is, in fact, **highly sensitive to pain** due to its rich nerve supply. - This rich innervation contributes significantly to the pain experienced in **fractures** and **bone bruises**. *It is highly vascular* - The periosteum is indeed **highly vascular**, containing numerous blood vessels that supply nutrients to the underlying bone [1]. - This extensive blood supply is crucial for **bone health**, maintenance, and repair, especially after injury. *It does not cover the articular surface of the bones* - This statement is correct; the periosteum **does not cover the articular surfaces** of bones. - Articular surfaces are instead covered by **articular cartilage**, which provides a smooth, low-friction surface for joint movement [2]. *It is pierced by the fibers of Sharpey's* - This statement is correct; **Sharpey's fibers** are collagenous fibers that extend from the periosteum into the outer circumferential lamellae of the bone. - These fibers serve to **anchor the periosteum firmly** to the bone, providing structural integrity.
Question 475: Lymphatic follicles are not seen in:
- A. Spleen
- B. Lymph node
- C. Tonsil
- D. Thymus (Correct Answer)
Explanation: ***Thymus*** - The thymus is primarily involved in **T-cell maturation** [1] and does not contain **lymphatic follicles**. - Its cortex and medulla are organized for T-cell education and selection, lacking the B-cell zones characteristic of follicles. *Spleen* - The **white pulp** of the spleen is rich in **lymphatic follicles**, which are sites of B-cell proliferation and differentiation. - These follicles are crucial for mounting immune responses against blood-borne pathogens. *Lymph node* - Lymph nodes are characterized by abundant **lymphatic follicles** in their cortex, containing primarily **B lymphocytes** [1]. - These follicles enlarge and form **germinal centers** during an active immune response. *Tonsil* - Tonsils are part of the **mucosa-associated lymphoid tissue (MALT)** and contain numerous **lymphatic follicles**. - These follicles help in initiating immune responses against pathogens entering through the oral cavity.
Question 476: The mucosal lining of the vagina is composed of cells:
- A. Stratified squamous non-keratinized (Correct Answer)
- B. Ciliated columnar epithelium
- C. Pseudostratified columnar epithelium
- D. Transitional epithelium
Explanation: ***Stratified squamous non-keratinized*** - The **vaginal epithelium** is composed of several layers of flattened, nucleated cells that provide **protection against friction** and resist pathogen entry during intercourse and childbirth [1]. - The **non-keratinized nature** ensures the mucosa remains moist and flexible, essential for its function. *Ciliated columnar epithelium* - This type of epithelium is found in locations like the **fallopian tubes** and parts of the **respiratory tract**, where cilia help in moving fluids or particles. - It does not provide the robust protective barrier required for the vagina. *Pseudostratified columnar epithelium* - This epithelium, characterized by nuclei at different levels giving a "pseudostratified" appearance, is typically found in the **trachea** and **bronchi**. In the uterus, however, the endometrial glands are lined by regular, tall, pseudostratified columnar cells during the proliferative phase [2]. - Its primary function is secretion and absorption, not the physical protection needed in the vagina. *Transitional epithelium* - Also known as **urothelium**, this type is specialized to accommodate stretching and is found in the **urinary bladder** and ureters. - It is not suited for the constant friction and protective role of the vaginal lining.
Question 477: Which layer of the epidermis is responsible for its proliferation and turnover?
- A. Spinous Layer (Stratum Spinosum)
- B. Basal Layer (Stratum Basale) (Correct Answer)
- C. Granular Layer (Stratum Granulosum)
- D. Stratum Lucidum (Clear Layer)
Explanation: ***Basal Layer (Stratum Basale)*** - This is the **deepest layer** of the epidermis, consisting of a single layer of **cuboidal or columnar cells** [1]. - It contains **basal keratinocytes**, which are highly mitotic and responsible for the continuous **proliferation and renewal** of the epidermis [1]. *Spinous Layer (Stratum Spinosum)* - This layer is characterized by the presence of **desmosomes** between keratinocytes, giving them a "spiny" appearance upon histological preparation. - While some cell division occurs in the deeper part of this layer, the primary function of this layer is to provide **strength and flexibility** to the epidermis. *Granular Layer (Stratum Granulosum)* - This layer is distinguished by the presence of **keratohyalin granules** and lamellar bodies within its cells [1]. - Its main role is in the **keratinization process**, where cells flatten and produce lipids that contribute to the skin's barrier function. *Stratum Lucidum (Clear Layer)* - This layer is a thin, translucent layer found only in **thick skin** areas like the palms of the hands and soles of the feet. - It is composed of **dead, flattened cells** and its primary function is to protect these high-wear areas, not to contribute to cell proliferation.
Question 478: 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 479: Which type of collagen is most abundant in hyaline cartilage?
- A. Type I
- B. Type II (Correct Answer)
- C. Type III
- D. Type IV
Explanation: ***Type II*** - **Type II collagen** is the predominant type found in **hyaline cartilage**, providing tensile strength and elasticity [1]. - It is crucial for the **structural integrity** and functionality of cartilage in articular surfaces [1]. *Type I* - Predominantly found in **bone**, tendons, and skin, contributing to tensile strength but not a major component of hyaline cartilage [2]. - It forms the structure of **fibrocartilage**, such as in the **intervertebral discs**. *Type IV* - Mainly located in **basement membranes** and plays a role in filtration and structural support of epithelial cells, not in hyaline cartilage. - It is critical in the formation of structures like **glomeruli** in kidneys, differing from cartilage's needs. *Type III* - Found in **reticular fibers** and supporting tissues throughout the body, important for organ structure but not prominent in hyaline cartilage. - Often associated with **vascular structures** and is not involved in the composition of cartilage.
Question 480: Stem cells are typically harvested from all except which?
- A. Liver (Correct Answer)
- B. Bone marrow
- C. Blood
- D. Adipose tissue
Explanation: ***Liver*** - **Liver** is not a recognized source of **pluripotent stem cells**, as it primarily contains specialized cells for hepatic functions. - While some **liver stem cells** exist, they are not generally sourced for therapies compared to other tissues like **bone marrow or adipose tissue** [1]. [2] *Adipose tissue* - **Adipose tissue** is a known source of **adipose-derived stem cells (ADSCs)**, which have regenerative potential [1]. - It is frequently used for **cosmetic and reconstructive applications** due to its ease of harvesting [1]. *Blood* - **Blood** contains **hematopoietic stem cells (HSCs)** primarily in the bone marrow, which can be harvested from peripheral blood after mobilization. - These stem cells are essential for **blood cell formation** and are effective in treatments for blood disorders [2]. *Bone marrow* - **Bone marrow** is a primary source of **hematopoietic stem cells**, crucial for **blood and immune system regeneration** [1]. [2] - It is commonly harvested for **transplants in conditions like leukemia** [2].
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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