Epithelial Cells

Epithelial cells line the gastrointestinal tract, respiratory tree, cardiovascular system, and genitourinary system and cover the skin. Which of the following cellular properties best distinguishes lining/coating epithelial cells from other cells/tissues in the body?

Digital slides illustrating various tissues are examined in the histology laboratory. Your instructor asks you to discuss the epithelium that lines the collecting ducts in the renal medulla (arrows, shown in the image). Identify the type of epithelium.

You continue to examine the digital slide described in Question 2 and identify a new visual field located near the tip of a renal papilla. The epithelium that lines these ducts (arrows, shown in the image) exhibits which of the following patterns of morphology?

Your instructor reminds you that epithelial cells have membrane channels that permit ions and small signaling molecules to pass between adjacent cells. Which of the following proteins forms these intercellular (gap) junctions?

A 50-year-old woman complains about a red papule on her right arm. Biopsy of the skin lesion reveals numerous, benign vascular channels filled with erythrocytes. The endothelial cells that line these vascular channels (arrows, shown in the image) exhibit which of the following patterns of epithelial tissue morphology?

A portion of the upper esophagus, collected at autopsy, is fixed with formalin, embedded in paraffin, sectioned at 6 µm, stained with H&E, and examined by light microscopy (shown in the image). Identify the type of epithelium.

You are investigating the role of cell adhesion molecules in embryonic development. Sections of a gastrula-stage mouse embryo are stained with periodic acid-Schiff reagent and counterstained with methylene blue. Which of the following families of proteins forms anchoring junctions between adjacent epithelial cells in the neural ectoderm of this embryo (arrow, shown in the image)?

Further examination of the embryo described in Question 7 reveals fluid-filled cavities above and below the amnion (shown in the image). Which of the following proteins plays an important role in regulating fluid transport and cavity formation in this embryo?

A 58-year-old man presents with a pigmented skin lesion on the lateral aspect of his right leg. A punch biopsy of the skin lesion is examined by light microscopy. Which of the following types of epithelium describes the patient's epidermis (indicated by the double arrow, shown in the image)?

Further examination of the skin biopsy described in Question 9 reveals the ducts of sweat glands (arrows, shown in the image). Which of the following types of epithelium lines these excretory channels?

A 25-year-old woman spends an afternoon raking leaves. Later that evening, she discovers fluid-filled blisters on the palms of her hands. Leakage of fluid from dermal capillaries at sites of minor injury in the hands of this patient is regulated by changes in which of the following intercellular junctions?

A 64-year-old man presents with a small mass on the inner surface of his lower lip. Biopsy of the mass reveals chronic inflammatory cells. As you examine the biopsy, you observe a large sweat duct surrounded by loose connective tissue (shown in the image). Identify the type of epithelium.

A 10-year-old girl scrapes her elbow on the sidewalk while skateboarding. Physical examination reveals a 5-cm superficial skin abrasion. Which of the following cellular processes regulates regeneration of the epidermis in this patient's superficial abrasion?

A 58-year-old woman presents with painless hematuria (blood in her urine). Urine cultures are negative for E. coli. A biopsy of the urinary bladder is examined in the pathology department (shown in the image). Identify the type of epithelium.

A section of trachea obtained at autopsy is stained with H&E and examined at high magnification (shown in the image). Identify the type of the lining epithelium.

Which of the following membrane junctions anchors the epithelial cells described in Question 15 to extracellular matrix molecules in the underlying basal lamina?

Which of the following proteins regulates the motility of cilia found along the apical membrane domain of the columnar epithelial cells described in Questions 15 and 16?

A biopsy of small intestine is examined at high magnification in the pathology department. Identify the apical membrane feature indicated by the arrows (shown in the image).

Electron microscopic examination of the epithelial cells described in this image reveals basolateral membrane infoldings (interdigitations). What is the most likely function of this membrane specialization?

A section of the intestinal biopsy described in Questions 18 and 19 is stained with periodic acid-Schiff (PAS) and examined at high magnification (shown in the image). Identify the type of epithelium.

Which of the following terms best describes the PAS-positive goblet cells identified in the image for Question 20?

Organs of the anterior neck are examined by a double-headed microscope. The pathology resident asks you to describe the small, tightly packed cells with central nuclei (shown in the image). These cells exhibit which of the following patterns of epithelial cell differentiation?

A sample of the epididymis, collected at autopsy, is examined by light microscopy in the pathology department. The nuclei of sperm are visible within the lumen of the duct. Epithelial cells lining the epididymis exhibit long stereocilia (shown in the image). Which of the following proteins determines the shape and size of these specialized apical membrane structures?

You attend a lecture on the physiology of lactation and breast-feeding. Under the influence of pregnancy-associated hormones, epithelial cells of the mammary gland secrete lipids, carbohydrates, and proteins. The lipid components of breast milk are released from the apical surface of the glandular epithelial cells as a lipid droplet within an envelope of the plasma membrane. Which of the following terms best describes this mechanism of secretion?

A section of the submandibular gland is stained with H&E and examined in the histology laboratory (shown in the image). The secretory units indicated by the arrows are composed primarily of which of the following types of epithelial cells?

In addition to collagen and proteoglycan, the basal lamina of the epithelial cells identified in Question 25 consists of which of the following structural proteins?

The distribution of organelles in cultured endothelial cells is examined using immunocytochemical techniques. A peripheral web of filamentous proteins is identified by confocal fluorescence microscopy (arrowhead, shown in the image). This web consists primarily of which of the following filamentous proteins?

A 68-year-old woman presents with a breast lump that she discovered 5 days ago. A biopsy reveals ductal carcinoma. Immunohistochemical assays are performed to investigate the role of cell adhesion molecules in malignancy. In contrast to normal ductal epithelial cells, this patient's cancer cells exhibit decreased expression of a cell adhesion protein (absence of brown stain indicated by the asterisk, shown in the image). Which of the following cell adhesion proteins was most likely down-regulated in this patient's ductal carcinoma?

A 58-year-old woman with a history of diabetes complains of swelling of her ankles. Physical examination reveals edema of the lower extremities. A kidney biopsy is obtained. Which of the following histochemical stains can be used to highlight the patient's glomerular basement membrane when examined by light microscopy?

A neurula-stage mouse embryo is stained by immunohistochemistry with monoclonal antibodies directed to stage-specific embryonic antigens. A marker for embryonic ectoderm is colored brown, and a marker for early mesoderm is colored red. Which of the following terms best describes the region of the embryo indicated by the asterisk (shown in the image)?