Histology Practice Questions

Q: What is the primary function of Schwann cells?

Form myelin sheath. ***Form myelin sheath*** - **Schwann cells** are glial cells found in the **peripheral nervous system** that wrap around axons to form the myelin sheath [1], [3]. - The **myelin sheath** acts as an electrical insulator, increasing the speed of nerve impulse conduction via **saltatory conduction** [2]. - This is the **primary and most characteristic function** of Schwann cells in the PNS [3]. *Part of the central nervous system* - Schwann cells are exclusively found in the **peripheral nervous system (PNS)**, not the CNS [4]. - In the **central nervous system (CNS)**, **oligodendrocytes** are responsible for myelin formation [1], [4]. *Derived from neural crest cells* - While Schwann cells are indeed derived from **neural crest cells**, this describes their **embryological origin**, not their function. - Many other cell types (melanocytes, neurons of peripheral ganglia) are also neural crest derivatives. *Present in both myelinated and unmyelinated nerve fibers* - While Schwann cells are associated with both fiber types, this describes their **distribution**, not their primary function [1], [3]. - In unmyelinated fibers, Schwann cells envelop multiple axons without forming concentric myelin layers [1].

Q: In the central nervous system, which cells are responsible for the formation of the myelin sheath of neurons?

Oligodendroglia cells. ***Oligodendroglia cells*** - **Oligodendroglia cells (oligodendrocytes)** are responsible for forming the **myelin sheath** around axons in the **central nervous system** (CNS) [2]. - Each oligodendrocyte can myelinate **multiple axons** (up to 50 segments), providing insulation that speeds up nerve impulse conduction via **saltatory conduction** [3], [4]. - This is a key distinguishing feature from Schwann cells in the PNS [3]. *Astrocytes* - **Astrocytes** are star-shaped glial cells that play a crucial role in providing **nutritional support** to neurons, regulating the **blood-brain barrier**, and maintaining the **extracellular environment**. - They do not form myelin; instead, they are involved in structural support, repair within the CNS, and neurotransmitter recycling [1]. *Schwann cells* - **Schwann cells** are the myelin-forming cells of the **peripheral nervous system** (PNS) [2]. - Unlike oligodendrocytes, each Schwann cell typically myelinates only a **single segment of one axon** [3], [4]. - This is the key anatomical difference between CNS and PNS myelination. *Microglia* - **Microglia** are the resident **immune cells** of the CNS, derived from mesoderm [1]. - They act as macrophages, responding to injury and infection, but play no role in myelin formation [1], [3]. - They are involved in immune surveillance and phagocytosis of debris [1].

Q: What type of epithelial lining is found on the lingual surface of the epiglottis?

Stratified Squamous Epithelium. ***Stratified Squamous Epithelium*** - The **lingual surface** of the epiglottis is exposed to the **abrasive effects of food** during swallowing, requiring a protective, wear-and-tear resistant lining. - **Stratified squamous epithelium** (non-keratinized) provides this necessary protection due to its multiple layers of cells. - This is the same epithelium found in the **oral cavity and esophagus**, adapted for mechanical stress. *Simple Cuboidal Epithelium* - This type of epithelium is typically found in **glands and kidney tubules**, designed for secretion and absorption, not protection against abrasion. - It consists of a single layer of cube-shaped cells and would be inadequate for the mechanical stresses on the epiglottis. *Pseudostratified Ciliated Columnar Epithelium* - This epithelium is characteristic of the **respiratory tract**, specifically the **laryngeal surface** of the epiglottis, where it helps in trapping particles and moving mucus. - Its primary function is mucociliary clearance, which is not the main requirement for the lingual surface. *Simple Columnar Epithelium* - This epithelium is found in the **gastrointestinal tract** (stomach, intestines) where it functions primarily in **secretion and absorption**. - It consists of a single layer of tall cells and would not provide adequate protection against the mechanical trauma on the lingual surface of the epiglottis.

Q: Epithelial lining of the urinary bladder is?

Transitional epithelium. ***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.

Q: Intracytoplasmic Nissl granules are found in?

Perikaryon of a neuron. ***Perikaryon of a neuron*** - **Nissl granules**, also known as **Nissl bodies**, are aggregates of **rough endoplasmic reticulum (RER)** and free **ribosomes** within the cytoplasm of neurons [1]. - They are primarily found in the **perikaryon** (cell body) and dendrites of neurons, where they are involved in **protein synthesis** for neural function and repair [1], [2]. *Smooth muscle* - **Smooth muscle cells** lack Nissl granules and do not possess the specialized rough endoplasmic reticulum structures characteristic of neurons. - Their cytoplasm contains abundant **actin** and **myosin** filaments arranged to allow for slow, sustained contractions. *Skeletal muscle* - **Skeletal muscle fibers** are characterized by highly organized contractile proteins (sarcomeres) and a specialized **sarcoplasmic reticulum** for calcium storage. - They do not contain Nissl granules; their extensive rough endoplasmic reticulum is not organized into such prominent aggregates. *Cardiac muscle* - **Cardiac muscle cells** contain a well-developed sarcoplasmic reticulum and numerous mitochondria to support continuous contractile activity. - Like other muscle types, they lack the specific granular aggregates of rough endoplasmic reticulum known as Nissl bodies, which are unique to neurons.

Q: Which substance is secreted by the cells of the stratum intermedium?

Alkaline phosphatase.. ***Alkaline phosphatase*** - Cells of the **stratum intermedium** are known to secrete and be rich in **alkaline phosphatase**. - This enzyme plays a crucial role in dental hard tissue formation, particularly during **enamel maturation**. *Hyaluronic acid* - **Hyaluronic acid** is a component of the **extracellular matrix** found in various connective tissues throughout the body, but it is not specifically secreted by the stratum intermedium. - Its primary functions include lubrication and tissue hydration. *Acid phosphatase* - **Acid phosphatase** is an enzyme found in lysosomes and is involved in various catabolic processes, particularly in breaking down organic phosphates. - It is not a characteristic secretion of the stratum intermedium during tooth development. *None of the options* - This option is incorrect because **alkaline phosphatase** is indeed secreted by the cells of the stratum intermedium. - The stratum intermedium is highly active metabolically, and the presence of this enzyme is vital for its role in enamel formation.

Q: Mature bone is otherwise called?

Lamellar bone. ***Lamellar bone*** - **Lamellar bone** is the characteristic form of mature bone, organized into parallel layers or concentric circles around a central canal [1]. - This highly organized structure provides **optimal mechanical strength** and is found in the adult skeleton [1]. *Woven bone* - **Woven bone** is immature, rapidly formed bone, often seen during fetal development, fracture repair, and in some pathological conditions [1, 2]. - It is characterized by its **disorganized collagen fibers** and lower mechanical strength compared to lamellar bone [1, 2]. *Irregular bone* - "Irregular bone" is not a recognized histological classification for mature bone. Bone types are generally classified by their microstructure, such as woven or lamellar. - This term usually refers to the **shape of certain bones** (e.g., vertebrae, sacrum), not their tissue maturity or structure. *Resorbing bone* - **Resorbing bone** refers to bone tissue undergoing degradation by osteoclasts as part of the continuous bone remodeling process. - This is a functional state of bone, not a structural classification of mature bone itself.

Q: Which of the following types of cells does not migrate from the base of the crypt to the ends of villi and is unique in this characteristic?

Paneth cell. ***Paneth cell*** - **Paneth cells** are unique among intestinal epithelial cells as they reside at the **base of the crypts of Lieberkühn** and do not migrate along the villi [1]. - They are responsible for secreting antimicrobial peptides, such as **defensins**, and other protective substances into the lumen, playing a crucial role in regulating intestinal flora and innate immunity [1]. *Enteroendocrine cell* - **Enteroendocrine cells** are found throughout the gastrointestinal tract, including the crypts and villi, and they **migrate upwards** from the crypt base as they differentiate [1]. - They secrete various **hormones** that regulate digestion and nutrient absorption, such as serotonin, cholecystokinin, and secretin [2]. *Goblet cell* - **Goblet cells** are mucin-producing cells that are interspersed among other epithelial cells and **migrate upwards** from the crypts to the villi [1]. - They contribute to the protective **mucus layer**, which lubricates the intestinal surface and provides a barrier against pathogens and digestive enzymes. *Enterocyte* - **Enterocytes**, the primary absorptive cells of the small intestine, originate in the crypts and then **migrate rapidly up the villi**, where they mature and perform their absorptive functions [1]. - They are characterized by **microvilli** on their apical surface, forming a brush border critical for nutrient absorption [2].

Q: Brunner's glands are seen in which part of the gastrointestinal tract?

Upper duodenum. ***Upper duodenum*** - **Brunner's glands** are distinctive submucosal glands found exclusively in the **proximal duodenum**. - These glands secrete an **alkaline mucus-rich fluid** that helps to neutralize the acidic chyme entering from the stomach and protect the duodenal mucosa. *Jejunum* - The jejunum is characterized by prominent **plicae circulares** (circular folds) and a high density of villi, but it lacks Brunner's glands. - Its primary role is **nutrient absorption**, and it does not require the extensive acid-neutralizing capacity provided by Brunner's glands. *Lower duodenum* - While the duodenum generally functions in digestion and absorption, Brunner's glands are specifically located in the **submucosa of the upper (first part) duodenum**, not the lower parts. - The lower duodenum primarily focuses on continued digestion and absorption, with fewer Peyer's patches forming towards its distal end. *Appendix* - The appendix is a small, finger-shaped organ protruding from the large intestine with a primary role in **immune function**, containing abundant lymphoid tissue. - It does not contain Brunner's glands, which are unique to the duodenum and involved in protecting the intestinal lining from gastric acid.

Question 1

What is the primary function of Schwann cells?

Accepted Answer

Form myelin sheath

Answer

Part of the central nervous system

Answer

Derived from neural crest cells

Answer

Present in both myelinated and unmyelinated nerve fibers

Question 2

In the central nervous system, which cells are responsible for the formation of the myelin sheath of neurons?

Accepted Answer

Oligodendroglia cells

Answer

Astrocytes

Answer

Schwann cells

Answer

Microglia

Question 3

What type of epithelial lining is found on the lingual surface of the epiglottis?

Accepted Answer

Stratified Squamous Epithelium

Answer

Simple Cuboidal Epithelium

Answer

Pseudostratified Ciliated Columnar Epithelium

Answer

Simple Columnar Epithelium

Question 4

Epithelial lining of the urinary bladder is?

Accepted Answer

Transitional epithelium

Answer

Squamous epithelium

Answer

Cuboidal epithelium

Answer

Columnar epithelium

Question 5

Intracytoplasmic Nissl granules are found in?

Accepted Answer

Perikaryon of a neuron

Answer

Smooth muscle

Answer

Skeletal muscle

Answer

Cardiac muscle

Question 6

Which substance is secreted by the cells of the stratum intermedium?

Accepted Answer

Alkaline phosphatase.

Answer

Hyaluronic acid.

Answer

Acid phosphatase.

Answer

None of the options.

Question 7

Which of the following statements about fibrous cartilage is true?

Accepted Answer

It is made of dense collagen fibers and lacks a perichondrium.

Answer

None of the options.

Answer

It serves as a transitional layer between hyaline cartilage and tendon or ligament, but this is not its primary characteristic.

Answer

This cartilage is strong but not the strongest among all types.

Question 8

Mature bone is otherwise called?

Accepted Answer

Lamellar bone

Answer

Woven bone

Answer

Irregular bone

Answer

Resorbing bone

Question 9

Which of the following types of cells does not migrate from the base of the crypt to the ends of villi and is unique in this characteristic?

Accepted Answer

Paneth cell

Answer

Enteroendocrine cell

Answer

Goblet cell

Answer

Enterocyte

Question 10

Brunner's glands are seen in which part of the gastrointestinal tract?

Accepted Answer

Upper duodenum

Answer

Jejunum

Answer

Lower duodenum

Answer

Appendix

Histology — MCQs

Histology — MCQs

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