A pathologist examining a tissue sample notes the presence of pseudostratified columnar epithelium with goblet cells and cilia. This tissue was most likely obtained from which of the following locations?
Q2
An investigator is studying cellular repair mechanisms in various tissues. One of the samples being reviewed is from the anterior horn of the spinal cord of a patient who was involved in a snowboard accident. Pathologic examination of the biopsy specimen shows dispersion of the Nissl bodies, swelling of the neuronal body, and a displacement of the nucleus to the periphery in numerous cells. Which of the following is the most likely explanation for the observed findings?
Q3
An investigator is examining tissue samples from various muscle tissue throughout the body. She notices that biopsies collected from a specific site have a high concentration of sarcoplasmic reticulum, mitochondria, and myoglobin; they also stain poorly for ATPase. Additionally, the cell surface membranes of the myocytes in the specimen lack voltage-gated calcium channels. These myocytes are found in the greatest concentration at which of the following sites?
Q4
A 52-year-old woman sees you in your office with a complaint of new-onset headaches over the past few weeks. On exam, you find a 2 x 2 cm dark, irregularly shaped, pigmented lesion on her back. She is concerned because her father recently passed away from skin cancer. What tissue type most directly gives rise to the lesion this patient is experiencing?
Q5
A 10-year-old boy is brought to his pediatrician over concern for a 2-month history of headaches. Recently, the patient has been experiencing nausea and vomiting, along with some difficulty with coordination during soccer practice last week. On exam, the patient's temperature is 98.2°F (36.8°C), blood pressure is 110/80 mmHg, pulse is 72/min, and respirations are 14/min. On further evaluation, the patient is found to have a well-encapsulated posterior fossa mass. The patient undergoes surgical resection, and the mass is found to be positive for GFAP. Which of the following is derived from the same embryologic germ layer as the cells that comprise this tumor?
Q6
A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?
Q7
A 35-year-old woman presents to a pre-operative evaluation clinic prior to an elective cholecystectomy. She has a 5 pack-year smoking history. The anesthesiologist highly recommends to discontinue smoking for at least 8 weeks prior to the procedure for which she is compliant. What is the most likely histology of her upper respiratory tract's epithelial lining at the time of her surgery?
Q8
A 23-year-old man comes to the physician for evaluation of decreased hearing, dizziness, and ringing in his right ear for the past 6 months. Physical examination shows multiple soft, yellow plaques and papules on his arms, chest, and back. There is sensorineural hearing loss and weakness of facial muscles bilaterally. His gait is unsteady. An MRI of the brain shows a 3-cm mass near the right internal auditory meatus and a 2-cm mass at the left cerebellopontine angle. The abnormal cells in these masses are most likely derived from which of the following embryological structures?
Q9
An investigator is conducting a study to document the histological changes in the respiratory tree of a chronic smoker. He obtains multiple biopsy samples from the respiratory system of a previously healthy 28-year-old man. Histopathological examination of one sample shows simple cuboidal cells with a surrounding layer of smooth muscle. Chondrocytes and goblet cells are absent. This specimen was most likely obtained from which of the following parts of the respiratory system?
Q10
A 38-year-old man comes to the physician because of a 6-month history of chest discomfort and progressive dyspnea. He cannot do daily chores without feeling out of breath. He was diagnosed in childhood with a milder X-linked dystrophinopathy that has caused progressive proximal muscle weakness and gait abnormalities over the years. Physical examination shows a waddling gait and weak patellar reflexes. Cardiovascular examination shows a holosystolic murmur, displaced point of maximal impulse, and bilateral pitting edema of the ankles. Laboratory studies show elevated levels of brain natriuretic peptide. Which of the following is the most likely underlying cause of this patient's muscle weakness?
Basic tissue types overview US Medical PG Practice Questions and MCQs
Question 1: A pathologist examining a tissue sample notes the presence of pseudostratified columnar epithelium with goblet cells and cilia. This tissue was most likely obtained from which of the following locations?
A. Bronchi (Correct Answer)
B. Small intestine
C. Skin
D. Esophagus
E. Urinary bladder
Explanation: ***Bronchi***
- The **bronchi**, as part of the respiratory tract, are lined with **pseudostratified columnar epithelium** that contains abundant **goblet cells** and **cilia** [1].
- **Cilia** help propel mucus and trapped particles out of the respiratory system, while **goblet cells** produce mucus to trap foreign substances [1].
*Small intestine*
- The small intestine is lined with **simple columnar epithelium** with **microvilli** (forming a brush border) and goblet cells, but it lacks **cilia**.
- Its primary function is nutrient absorption, not particulate clearance.
*Skin*
- The skin is covered by **stratified squamous epithelium**, specifically **keratinized stratified squamous epithelium**, which provides protection against abrasion and dehydration.
- It does not contain **goblet cells**, **cilia**, or **pseudostratified columnar epithelium**.
*Esophagus*
- The esophagus is lined with **non-keratinized stratified squamous epithelium**, designed to protect against mechanical abrasion during food passage.
- It lacks **goblet cells**, **cilia**, and **pseudostratified columnar epithelium**.
Question 2: An investigator is studying cellular repair mechanisms in various tissues. One of the samples being reviewed is from the anterior horn of the spinal cord of a patient who was involved in a snowboard accident. Pathologic examination of the biopsy specimen shows dispersion of the Nissl bodies, swelling of the neuronal body, and a displacement of the nucleus to the periphery in numerous cells. Which of the following is the most likely explanation for the observed findings?
A. Neurodegenerative changes
B. Neuronal aging
C. Central chromatolysis (Correct Answer)
D. Reactive astrogliosis
E. Wallerian degeneration
Explanation: ***Central chromatolysis***
- This process is a **response to axonal injury**, where the neuron undergoes characteristic morphological changes to prepare for regeneration.
- Key features include **dispersion of Nissl bodies**, **neuronal swelling**, and **nucleus displacement to the periphery**, all indicative of an attempt at cellular repair.
*Neurodegenerative changes*
- These typically involve **neuronal loss** and accumulation of **abnormal protein deposits**, rather than an attempt at cellular repair.
- The observed features (swelling, Nissl body dispersion) are part of an acute injury response, not chronic degeneration.
*Neuronal aging*
- Though aging neurons can accumulate **lipofuscin** and show some atrophy, they do not typically present with the acute, dramatic changes of cell body swelling and peripheral nucleus displacement described.
- Aging is a slow, progressive process, distinct from an acute response to injury from an accident.
*Reactive astrogliosis*
- This refers to the **proliferation and hypertrophy of astrocytes** in response to CNS injury.
- While it's a component of the injury response, it describes glial cell changes, not the neuronal body changes observed in the question.
*Wallerian degeneration*
- This process describes the **degeneration of the axon distal to the site of injury**, as well as the myelin sheath.
- It does not characterize the **changes occurring within the neuronal cell body** (soma), which are the focus of the question.
Question 3: An investigator is examining tissue samples from various muscle tissue throughout the body. She notices that biopsies collected from a specific site have a high concentration of sarcoplasmic reticulum, mitochondria, and myoglobin; they also stain poorly for ATPase. Additionally, the cell surface membranes of the myocytes in the specimen lack voltage-gated calcium channels. These myocytes are found in the greatest concentration at which of the following sites?
A. Ventricular myocardium
B. Tunica media
C. Lateral rectus muscle
D. Glandular myoepithelium
E. Semispinalis muscle (Correct Answer)
Explanation: ***Semispinalis muscle***
- The described characteristics—**high concentration of sarcoplasmic reticulum, mitochondria, and myoglobin** with **poor ATPase staining**—are hallmarks of **Type I (slow-twitch oxidative) skeletal muscle fibers**.
- Postural muscles like the **semispinalis** (part of the erector spinae group) are predominantly composed of Type I fibers adapted for sustained, aerobic contraction to maintain posture.
- These fibers appear **red** due to high myoglobin content, have abundant mitochondria for aerobic metabolism, and stain **poorly for ATPase** (distinguishing them from Type II fast-twitch fibers).
- While all skeletal muscle does possess voltage-gated calcium channels for excitation-contraction coupling, the overall profile best matches slow-twitch postural muscles.
*Ventricular myocardium*
- While cardiac muscle has high mitochondria, myoglobin, and sarcoplasmic reticulum, it **does possess L-type voltage-gated calcium channels** on the sarcolemma, which are essential for cardiac excitation-contraction coupling.
- Cardiac muscle relies on **both** extracellular Ca²⁺ influx through these channels and calcium-induced calcium release from the SR.
- Cardiac muscle typically stains **strongly for ATPase**, not poorly.
*Tunica media*
- Composed of **vascular smooth muscle** with poorly developed sarcoplasmic reticulum and relatively few mitochondria compared to skeletal or cardiac muscle.
- Smooth muscle relies heavily on **extracellular calcium influx** and the calmodulin pathway for contraction.
- Not characterized by high myoglobin content.
*Lateral rectus muscle*
- This extraocular muscle contains predominantly **Type IIb fast-twitch glycolytic fibers** adapted for rapid, precise eye movements.
- These fibers have **low myoglobin** (white muscle), fewer mitochondria, and stain **strongly for ATPase**.
- Opposite profile from the described tissue.
*Glandular myoepithelium*
- Myoepithelial cells are specialized contractile cells in secretory glands with minimal sarcoplasmic reticulum and mitochondria.
- Function is brief contraction for secretion expulsion, not sustained aerobic work.
- Do not exhibit the high oxidative capacity described.
Question 4: A 52-year-old woman sees you in your office with a complaint of new-onset headaches over the past few weeks. On exam, you find a 2 x 2 cm dark, irregularly shaped, pigmented lesion on her back. She is concerned because her father recently passed away from skin cancer. What tissue type most directly gives rise to the lesion this patient is experiencing?
A. Neural crest cells (Correct Answer)
B. Endoderm
C. Mesoderm
D. Ectoderm
E. Neuroectoderm
Explanation: ***Neural crest cells***
- The suspected lesion, given its description and the patient's family history of skin cancer, is likely a **melanoma**.
- Melanoma originates from **melanocytes**, which are derived from **neural crest cells** during embryonic development.
*Endoderm*
- The endoderm gives rise to the **lining of the gastrointestinal and respiratory tracts**, as well as organs such as the liver and pancreas.
- It is not involved in the formation of melanocytes or skin lesions like melanoma.
*Mesoderm*
- The mesoderm forms tissues such as **muscle, bone, cartilage, connective tissue**, and the circulatory system.
- It does not directly give rise to melanocytes, which are the cells of origin for melanoma.
*Ectoderm*
- The ectoderm gives rise to the **epidermis, nervous system**, and sensory organs.
- While melanocytes are found in the epidermis, they are specifically derived from the **neural crest (a sub-population of ectoderm)**, not the general ectoderm.
*Neuroectoderm*
- Neuroectoderm specifically refers to the ectoderm that develops into the **nervous system**.
- While neural crest cells originate from the neuroectoderm, "neural crest cells" is a more precise answer for the origin of melanocytes.
Question 5: A 10-year-old boy is brought to his pediatrician over concern for a 2-month history of headaches. Recently, the patient has been experiencing nausea and vomiting, along with some difficulty with coordination during soccer practice last week. On exam, the patient's temperature is 98.2°F (36.8°C), blood pressure is 110/80 mmHg, pulse is 72/min, and respirations are 14/min. On further evaluation, the patient is found to have a well-encapsulated posterior fossa mass. The patient undergoes surgical resection, and the mass is found to be positive for GFAP. Which of the following is derived from the same embryologic germ layer as the cells that comprise this tumor?
A. Ependymal cells (Correct Answer)
B. Nucleus pulposus
C. Schwann cells
D. Microglia
E. Melanocytes
Explanation: ***Ependymal cells***
- The tumor described is a **pilocytic astrocytoma**, a common **posterior fossa tumor** in children, characterized by its **well-encapsulated** nature and **GFAP positivity**, indicating an **astrocytic origin**.
- **Astrocytes** develop from the **neuroectoderm/neural tube**, as do **ependymal cells**, which line the ventricles and central canal of the spinal cord.
*Nucleus pulposus*
- The **nucleus pulposus** is a remnant of the **notochord**, which originates from the **mesoderm**.
- This embryological origin is distinct from the **neuroectodermal** origin of the tumor cells.
*Schwann cells*
- **Schwann cells** are derived from the **neural crest**, which is also **ectodermal** but represents a different lineage than the **neural tube**.
- While both contribute to the nervous system, **neural crest cells** form the peripheral nervous system, whereas the **neural tube** forms the central nervous system.
*Microglia*
- **Microglia** are the immune cells of the CNS and are derived from the **mesoderm**, specifically from **monocytes** in the yolk sac.
- Their origin is distinct from the **neuroectodermal** lineage of astrocytes.
*Melanocytes*
- **Melanocytes** are pigment-producing cells found in the skin, hair, and eyes, and they are derived from the **neural crest**.
- This makes their embryological origin different from the **neural tube** cells that give rise to astrocytes.
Question 6: A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?
A. "Does the diarrhea typically precede the constipation, or vice-versa?"
B. "Is the diarrhea foul-smelling?"
C. "Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"
D. "Are the symptoms worse in the morning or at night?"
E. "Can you tell me more about the symptoms you have been experiencing?" (Correct Answer)
Explanation: ***Can you tell me more about the symptoms you have been experiencing?***
- This **open-ended question** encourages the patient to provide a **comprehensive narrative** of their symptoms, including details about onset, frequency, duration, alleviating/aggravating factors, and associated symptoms, which is crucial for diagnosis.
- In a patient presenting with vague, intermittent symptoms like alternating constipation and diarrhea, allowing them to elaborate freely can reveal important clues that might not be captured by more targeted questions.
*Does the diarrhea typically precede the constipation, or vice-versa?*
- While knowing the sequence of symptoms can be helpful in understanding the **pattern of bowel dysfunction**, it is a very specific question that might overlook other important aspects of the patient's experience.
- It prematurely narrows the focus without first obtaining a broad understanding of the patient's overall symptomatic picture.
*Is the diarrhea foul-smelling?*
- Foul-smelling diarrhea can indicate **malabsorption** or **bacterial overgrowth**, which are important to consider in some gastrointestinal conditions.
- However, this is a **specific symptom inquiry** that should follow a more general exploration of the patient's symptoms, as it may not be relevant if other crucial details are missed.
*Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life*
- Quantifying pain intensity is useful for assessing the **severity of discomfort** and monitoring changes over time.
- However, for a patient with intermittent rather than acute, severe pain, understanding the **character, location, and triggers** of the pain is often more diagnostically valuable than just a numerical rating initially.
*Are the symptoms worse in the morning or at night?*
- Diurnal variation can be relevant in certain conditions, such as inflammatory bowel diseases where nocturnal symptoms might be more concerning, or functional disorders whose symptoms might be stress-related.
- This is another **specific question** that should come after gathering a more complete initial picture of the patient's symptoms to ensure no key information is overlooked.
Question 7: A 35-year-old woman presents to a pre-operative evaluation clinic prior to an elective cholecystectomy. She has a 5 pack-year smoking history. The anesthesiologist highly recommends to discontinue smoking for at least 8 weeks prior to the procedure for which she is compliant. What is the most likely histology of her upper respiratory tract's epithelial lining at the time of her surgery?
A. Simple squamous
B. Simple columnar
C. Pseudostratified columnar (Correct Answer)
D. Stratified squamous
E. Stratified columnar
Explanation: ***Pseudostratified columnar***
- The upper respiratory tract is normally lined by **pseudostratified ciliated columnar epithelium** with goblet cells, which is crucial for mucociliary clearance.
- While smoking can initially cause **squamous metaplasia**, discontinuing smoking for 8 weeks allows for significant, if not complete, **reversal of these changes** back to the normal pseudostratified columnar epithelium.
*Simple squamous*
- This type of epithelium is found in areas designed for efficient **gas exchange** (e.g., alveoli of the lungs) and is not typical for the conductive airways of the upper respiratory tract.
- It lacks the **cilia and goblet cells** necessary for clearing inhaled particles and pathogens.
*Simple columnar*
- **Simple columnar epithelium** is found in regions like the lining of the gastrointestinal tract (e.g., stomach, small and large intestines) and is not characteristic of the upper respiratory tract.
- While it can have goblet cells, it typically lacks **cilia** for respiratory clearance.
*Stratified squamous*
- **Stratified squamous epithelium** is found in areas subject to friction and abrasion, such as the oral cavity, pharynx, and esophagus.
- While chronic smoking can induce **squamous metaplasia** in the respiratory tract, an 8-week cessation period would likely result in the reversal of this change back to the normal type.
*Stratified columnar*
- **Stratified columnar epithelium** is a relatively rare type found in specific locations like parts of the male urethra and some large excretory ducts.
- It is not the normal or even a common metaplastic lining for the human upper respiratory tract.
Question 8: A 23-year-old man comes to the physician for evaluation of decreased hearing, dizziness, and ringing in his right ear for the past 6 months. Physical examination shows multiple soft, yellow plaques and papules on his arms, chest, and back. There is sensorineural hearing loss and weakness of facial muscles bilaterally. His gait is unsteady. An MRI of the brain shows a 3-cm mass near the right internal auditory meatus and a 2-cm mass at the left cerebellopontine angle. The abnormal cells in these masses are most likely derived from which of the following embryological structures?
A. Surface ectoderm
B. Neural tube
C. Neural crest (Correct Answer)
D. Notochord
E. Mesoderm
Explanation: ***Neural crest***
- The patient's symptoms (bilateral sensorineural hearing loss, facial weakness, unsteady gait, central masses) along with cutaneous lesions (soft, yellow plaques) are highly suggestive of **Neurofibromatosis type 2 (NF2)**.
- NF2 is characterized by **vestibular schwannomas** (acoustic neuromas) and other CNS tumors, which are derived from **Schwann cells**. Schwann cells, along with melanocytes and other peripheral nervous system components, originate from the **neural crest**.
*Surface ectoderm*
- The surface ectoderm forms structures such as the **epidermis**, hair, nails, and anterior pituitary.
- While the skin lesions are present, the primary tumors (schwannomas) are not derived from the surface ectoderm.
*Neural tube*
- The neural tube gives rise to the **central nervous system** (brain and spinal cord) and motor neurons.
- While the tumors affect the brain and cranial nerves, the specific cell type forming schwannomas (Schwann cells) does not originate directly from the neural tube.
*Notochord*
- The notochord induces the formation of the neural tube and eventually degenerates, contributing to the **nucleus pulposus** of the intervertebral discs.
- It is not involved in the pathogenesis or cellular origin of schwannomas.
*Mesoderm*
- The mesoderm gives rise to connective tissues, blood, bone, muscle, and most internal organs.
- While some tumors can have mesodermal origins, schwannomas are neuroectodermal in origin.
Question 9: An investigator is conducting a study to document the histological changes in the respiratory tree of a chronic smoker. He obtains multiple biopsy samples from the respiratory system of a previously healthy 28-year-old man. Histopathological examination of one sample shows simple cuboidal cells with a surrounding layer of smooth muscle. Chondrocytes and goblet cells are absent. This specimen was most likely obtained from which of the following parts of the respiratory system?
A. Terminal bronchiole (Correct Answer)
B. Alveolar sac
C. Main stem bronchus
D. Bronchiole
E. Respiratory bronchiole
Explanation: ***Terminal bronchiole***
- Terminal bronchioles are lined by **simple cuboidal epithelium** and contain surrounding **smooth muscle** but lack cartilage (chondrocytes) and goblet cells, matching the histological description.
- They represent the most distal purely conducting airways before respiratory bronchioles, where gas exchange begins.
*Alveolar sac*
- Alveolar sacs are primarily composed of **Type I and Type II pneumocytes** for gas exchange, and would not have a prominent smooth muscle layer or cuboidal cells in this described pattern.
- They are the terminal structures of the respiratory tree where gas exchange occurs, defined by very thin walls lacking cartilage and goblet cells.
*Main stem bronchus*
- The main stem bronchi are characterized by **pseudostratified ciliated columnar epithelium** with abundant **goblet cells** and contain **hyaline cartilage** (chondrocytes) in their walls.
- The presence of goblet cells and cartilage (chondrocytes) makes this option inconsistent with the given histological findings.
*Bronchiole*
- Bronchioles are generally lined by **ciliated columnar to cuboidal epithelium** with scattered goblet cells in larger ones, and they possess smooth muscle but lack cartilage.
- While they share some features with terminal bronchioles, the presence of goblet cells (even if sparse) distinguishes bronchioles from terminal bronchioles.
*Respiratory bronchiole*
- Respiratory bronchioles are distinguished by their walls having occasional **alveoli**, indicating the beginning of gas exchange. Their epithelium is cuboidal.
- They would not be described as having a "surrounding layer of smooth muscle" in isolation as clearly as a terminal bronchiole, and the presence of alveoli would be a key distinguishing feature.
Question 10: A 38-year-old man comes to the physician because of a 6-month history of chest discomfort and progressive dyspnea. He cannot do daily chores without feeling out of breath. He was diagnosed in childhood with a milder X-linked dystrophinopathy that has caused progressive proximal muscle weakness and gait abnormalities over the years. Physical examination shows a waddling gait and weak patellar reflexes. Cardiovascular examination shows a holosystolic murmur, displaced point of maximal impulse, and bilateral pitting edema of the ankles. Laboratory studies show elevated levels of brain natriuretic peptide. Which of the following is the most likely underlying cause of this patient's muscle weakness?
A. Increased number of CTG repeats in the DMPK gene
B. Interruption of microtubule depolymerization through stabilization of GDP-tubulin
C. Impaired connection of cytoskeletal actin filaments to membrane-bound dystroglycan (Correct Answer)
D. Cell–mediated cytotoxicity against skeletal muscle antigens in the endomysium
E. Defective lysine-hydroxylysine crosslinking of tropocollagen
Explanation: ***Impaired connection of cytoskeletal actin filaments to membrane-bound dystroglycan***
- The description of a **milder X-linked dystrophinopathy** with progressive muscle weakness and gait abnormalities, coupled with cardiac manifestations like a **holosystolic murmur** and elevated **BNP**, is characteristic of a **dystrophinopathy**, such as **Becker muscular dystrophy**.
- **Dystrophin** is a critical protein that links the **cytoskeletal actin filaments** to the **dystroglycan complex** at the sarcolemma, providing mechanical stability to muscle fibers. Impaired connection leads to muscle fragility and degeneration.
*Increased number of CTG repeats in the DMPK gene*
- This describes **myotonic dystrophy type 1**, which is an autosomal dominant condition, not X-linked.
- While it causes muscle weakness, it is also associated with **myotonia**, testicular atrophy, and cataracts, which are not mentioned.
*Interruption of microtubule depolymerization through stabilization of GDP-tubulin*
- This mechanism is associated with **chemotherapeutic agents** like taxanes (e.g., paclitaxel, docetaxel), which interfere with cell division.
- It does not explain a genetic, progressive muscle weakness disorder.
*Cell–mediated cytotoxicity against skeletal muscle antigens in the endomysium*
- This describes the pathophysiology of **polymyositis**, an **inflammatory myopathy**.
- Polymyositis is an autoimmune condition and does not typically present as an X-linked inherited disorder diagnosed in childhood.
*Defective lysine-hydroxylysine crosslinking of tropocollagen*
- This mechanism is characteristic of disorders affecting **collagen synthesis** and cross-linking, such as **Ehlers-Danlos syndrome**.
- These conditions primarily affect connective tissue, leading to joint hypermobility, skin hyperextensibility, and tissue fragility, not primarily progressive muscle weakness due to dystrophin deficiency.
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