Histo Test 1
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? (A) Actin (B) Desmin (C) Keratin (D) Tubulin (E) Vimentin
(A) Actin
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) Actin (B) Desmin (C) Lamin (D) Nestin (E) Tubulin
(A) Actin
You are studying cell migration during embryonic development. Neural tubes are harvested from post implantation mouse embryos and placed in culture on plastic dishes coated with fibronectin. Time-lapse imaging reveals neural crest cells migrating away from the explanted tissue. The cells are observed to undergo continuous changes in cell shape, including the formation and retraction of lamellipodia. What protein is the principal mediator of membrane ruffling and locomotion in these cultured cells? (A) Actin (B) Desmin (C) Lamin (D) Tubulin (E) Vimentin
(A) Actin
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? (A) Apical and basal membrane domains (B) Cell-cell anchoring junctions (C) Cell-extracellular matrix anchoring junctions (D) Communicating (gap) junctions (E) Pericellular lamina externa
(A) Apical and basal membrane domains
You attend a lecture on the physiology of lactation and breast-feeding. Under the influence of pregnancyassociated 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) Apocrine (B) Eccrine (C) Endocrine (D) Holocrine (E) Merocrine
(A) Apocrine
Release of cytochrome c from the organelle described in Question 16 activates which of the following cellular processes? (A) Apoptosis (B) Autophagy (C) Cell division (D) Cell motility (E) Exocytosis
(A) Apoptosis
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) Cadherin (B) Fibronectin (C) Integrin (D) Laminin (E) Selectin
(A) Cadherin
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)? (A) Cadherins (B) Cloudins (C) Integrins (D) Occludins (E) Selectins
(A) Cadherins
The gene for green fluorescent protein is modified by the addition of a signal sequence that targets the translation product to the lumen of the endoplasmic reticulum (ER). The distribution of the rough ER in a transfected myoblast cell line is monitored by confocal fluorescence microscopy (shown in the image). Which of the following families of proteins facilitates proper protein folding in the ER, cytoplasm, and nucleus of this muscle stem cell? (A) Chaperones (B) Clathrins (C) Cyclins (D) Lamins (E) Ubiquitin ligases
(A) Chaperones
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. (A) Ciliated pseudostratified columnar with goblet cells (B) Glandular epithelium (C) Keratinized stratified squamous (D) Nonkeratinized stratified squamous (E) Simple columnar with goblet cells
(A) Ciliated pseudostratified columnar with goblet cells
A 12-month-old boy is brought to the emergency room for examination of his right arm following a tumble at school. Radiologic examination of the limb reveals a recent fracture of the right ulna and evidence of several additional healing fractures. Further testing demonstrates that this child has osteogenesis imperfecta, an autosomal dominant genetic disease caused by mutations in the gene for which of the following structural proteins? (A) Collagen type I (B) Collagen type II (C) Elastin (D) Fibrillin-1 (E) Laminin
(A) Collagen type I
A 60-year-old woman presents with several small, pearly nodules on the back of her neck. A biopsy of one lesion reveals a basal cell carcinoma and adjacent areas of normal skin (shown in the image). The area indicated by the asterisk is typically composed of which of the following tissue types? (A) Dense, irregular connective tissue (B) Dense, regular connective tissue (C) Glandular epithelium (D) Skeletal muscle (E) Smooth muscle
(A) Dense, irregular connective tissue
Hepatocytes in a liver biopsy are examined by electron microscopy. The parallel lines with knob-like features (arrows, shown in the image) represent which of the following intracellular organelles? (A) Endoplasmic reticulum (B) Golgi apparatus (C) Mitochondria (D) Nucleus (E) Peroxisomes
(A) Endoplasmic reticulum
In patients with osteogenesis imperfecta, gene mutations that change which of the following amino acids can block the formation of collagen triple helices? (A) Glycine (B) Histidine (C) Leucine (D) Lysine (E) Proline
(A) Glycine
You are asked to lead a seminar on intracellular protein trafficking. What organelle provides a microenvironment for the posttranslational modification and sorting of membrane and secretory proteins? (A) Golgi apparatus (B) Lysosome (C) Peroxisome (D) Plasma membrane (E) Smooth endoplasmic reticulum
(A) Golgi apparatus
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)? (A) Keratinized stratified squamous (B) Nonkeratinized stratified squamous (C) Pseudostratified columnar (D) Stratified cuboidal (E) Transitional
(A) Keratinized stratified squamous
A 23-year-old man presents with a 6-month history of yellow skin and sclerae. Physical examination shows mild jaundice and peritoneal ascites. The patient is subsequently diagnosed with α-1-antitrypsin deficiency. A liver biopsy stained with PAS reveals globular inclusions of misfolded α-1-antitrypsin (shown in the image). The abundance of these abnormal glycoproteins has apparently overwhelmed normal degradation pathways. Which of the following cellular processes describes the normal mechanism for specifically targeting and degrading misfolded proteins within cells? (A) Activation of the caspase enzyme cascade (B) Activation of the ubiquitin-proteasome pathway (C) Delivery of acid hydrolases to lysosomes (D) Fusion of secretory vesicles with the plasma membrane (E) Generation of reactive oxygen species
(B) Activation of the ubiquitin-proteasome pathway
A 58-year-old obese man (BMI = 33 kg/m2 ) complains of headaches and blurry vision of 5-month duration. On physical examination, the blood pressure is 190/148 mm Hg. Malignant hypertension in this patient may be due, in part, to an increase in the serum concentration of which of the following adipocyte-produced hormones? (A) Adiponectin (B) Angiotensinogen (C) Estrogens (D) Leptin (E) Resistin
(B) Angiotensinogen
A 55-year-old woman learns that she has high levels of serum cholesterol (greater than 280 mg/dL normal less than 200 mg/dL) and is at increased risk for development of ischemic heart disease. The patient asks you to explain the normal pathway for serum cholesterol uptake and clearance. You explain to her that low-density lipoprotein (LDL) receptors present in her liver bind LDL cholesterol and internalize it by forming coated vesicles (endosomes). Which of the following structural proteins mediates LDL receptor internalization by organizing small buds of plasma membrane into endosomes? (A) Actin (B) Clathrin (C) Desmin (D) Laminin (E) Vimentin
(B) Clathrin
A 3-year-old girl is found to have extremely pliable skin. Her parents note that she bruises easily and that her joints can be hyperextended. Biochemical and genetic studies establish a diagnosis of Ehlers-Danlos syndrome. This patient's genetic disease is caused by an abnormal- ity or deficiency of which of the following proteins? (A) Actin (B) Collagen (C) Elastin (D) Fibrillin (E) Myosin
(B) Collagen
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) Cadherins (B) Connexins (C) Netrins (D) Perforins (E) Porins
(B) Connexions
A 43-year-old woman presents with a mass in her right breast that she first detected 4 months ago. A firm 4-cm mass is palpated on breast examination. An excisional biopsy is obtained (shown in the image). The area indi- cated by arrows is primarily composed of which of the following types of connective tissue? (A) Dense irregular (B) Dense regular (C) Elastic (D) Loose (E) Reticular
(B) Dense regular
A 65-year-old woman jogger with a history of tendonitis affecting the pes anserinus at the knee suffers a massive stroke and expires. A section of her left sartorius tendon is examined at autopsy (shown in the image). This col- lagen-rich connective tissue is important in transmitting force from muscle to bone. Which of the following best describes this type of connective tissue? (A) Dense irregular (B) Dense regular (C) Elastic (D) Loose (E) Reticular
(B) Dense regular
A 68-year-old man presents with a 2-week history of abdominal discomfort. A CT scan reveals a dilated and calcified segment of the abdominal aorta proximal to the bifurcation. Prior to surgery, the patient suffers a massive heart attack and expires. The abdominal aorta is exam- ined at autopsy (shown in the image). Loss of which of the following cellular/biochemical components of the aortic media contributed the most to the development of this patient's abdominal aneurysm? (A) Collagen type I fibers (B) Elastic fibers/lamellae (C) Heparin sulfate proteoglycans (D) Reticular (type III collagen) fibers (E) Smooth muscle bundles
(B) Elastic fibers/lamellae
In addition to providing body insulation and maintaining energy homeostasis, adipose tissue is considered to be an important organ for which of the following biological functions? (A) Calcium storage (B) Endocrine secretion (C) Hematopoiesis (D) Immune surveillance (E) Wound healing
(B) Endocrine secretion
Which of the following cells are responsible for the syn- thesis and deposition of collagens and other extracellular matrix proteins in the area of the breast biopsy specified in Question 3? (A) Adipocytes (B) Fibroblasts (C) Glandular epithelial cells (D) Macrophages (E) Plasma cells
(B) Fibroblasts
A 12-year-old girl has a 1.5-cm birthmark (benign con- genital nevus) removed from her left upper thigh under local anesthesia. Which of the following families of cell adhesion molecules is the principal component of the "provisional matrix" that mediates cell-to-matrix interactions during wound healing in this patient? (A) Cadherins (B) Fibronectins (C) Integrins (D) Laminins (E) Selectins
(B) Fibronectins
As part of your research, you investigate the role of cyclins and cyclin-dependent kinases in regulating ES cell growth in vitro. These rapidly dividing cells spend most of their time in which phase of the mitotic cell cycle? (A) G0 (B) G1 (C) G2 (D) M (E) S
(B) G1
Organs of the anterior neck are examined by a doubleheaded 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) Complex stratified (B) Glandular (C) Pseudostratified (D) Simple squamous (E) Stratified cuboidal
(B) Glandular
Which of the following components of connective tissue links cells to the extracellular matrix to help maintain tissue integrity and regulate cell behavior? (A) Proteoglycans (B) Glycoproteins (C) Collagen fibers (D) Elastic fibers (E) Glycosaminoglycans
(B) Glycoproteins
Which of the following membrane junctions anchors the epithelial cells described in Question 15 to extracellular matrix molecules in the underlying basal lamina? (A) Gap junctions (B) Hemidesmosomes (C) Macula adherens (D) Zonula adherens (E) Zonula occludens
(B) Hemidesmosomes
You are studying the role of mitochondrial dysfunction in alcoholic liver disease. Genes for an inner mitochondrial membrane protein and a red fluorescent protein are spliced, and the fusion protein is expressed in mouse embryo fibroblasts. The distribution of mitochondria in the transfected cells is visualized by confocal fluorescence microscopy (shown in the image). Inhibition of the electron transport chain in this organelle leads to which of the following reversible changes in cell behavior? (A) Extension of filopodia (B) Hydropic swelling (C) Intracellular lipid storage (D) Membrane ruffling (E) Protooncogene activation
(B) Hydropic swelling
The motor neurons described in Question 13 are labeled by immunocytochemistry using antibodies directed against a neuron-specific protein that helps maintain the shape of dendrites and axons. This structural protein forms which of the following intracellular organelles? (A) Endoplasmic reticulum (B) Intermediate filaments (C) Microfilaments (D) Microtubules (E) Plasma membrane
(B) Intermediate filaments
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? (A) Desmoplakin (B) Laminin (C) Talin (D) Vimentin (E) Vinculin
(B) Laminin
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) Differentiation of myoepithelial cells and wound contraction (B) Loss of cell contact inhibition of growth and motility (C) Platelet activation and intravascular coagulation (D) Proliferation of capillary endothelial cells (angiogenesis) (E) Stimulation of fibroblasts to deposit a provisional extracellular matrix
(B) Loss of cell contact inhibition of growth and motility
As part of your research, you examine integral membrane proteins in cleavage-stage mouse embryos using fluorescence microscopy (shown in the image). A pulse of high-intensity UV light is directed at a small patch on the surface of one blastomere, thereby causing an immediate loss of fluorescence emission (photobleaching). Over the next 10 minutes, fluorescence emission from this patch of membrane recovers. Which of the following cellular properties/processes best explains these experimental findings? (A) Lipid raft assembly (B) Membrane fluidity (C) Patching and capping (D) Protein trafficking (E) Receptor-mediated endocytosis
(B) Membrane fluidity
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. (A) Keratinized stratified squamous (B) Nonkeratinized stratified squamous (C) Pseudostratified columnar (D) Stratified cuboidal (E) Transitional
(B) Nonkeratinized stratified squamous
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. (A) Pseudostratified cuboidal (B) Simple columnar (C) Simple cuboidal (D) Simple squamous (E) Stratified columnar
(B) Simple columnar
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? (A) Pseudostratified cuboidal (B) Simple columnar (C) Simple cuboidal (D) Simple squamous (E) Stratified columnar
(B) Simple columnar
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) Pseudostratified columnar (B) Stratified columnar (C) Stratified cuboidal (D) Stratified squamous (E) Transitional
(B) Stratified columnar
The delicate stromal fibers described in question 5 are composed primarily of which of the following structural proteins? (A) Collagen type I (B) Collagen type II (C) Collagen type III (D) Elastin (E) Fibrillin
(C) Collagen type III
A section of the aorta is examined at autopsy using a special stain (shown in the image). Identify the tissue type in the region indicated by the double arrow. (A) Dense irregular connective tissue (B) Dense regular connective tissue (C) Elastic connective tissue (D) Reticular connective tissue (E) Smooth muscle tissue
(C) Elastic connective tissue
You join a research laboratory to investigate the growth and differentiation of human embryonic stem (ES) cells. These remarkable cells have been shown to differentiate into a wide variety of somatic cell types including (1) dopamine producing neurons, (2) cardiac myocytes, and (3) insulin-producing pancreatic islet cells. ES cells are similar or equivalent to which of the following populations of cells/tissues in the early embryo? (A) Amnion (B) Chorion (C) Epiblast (D) Hypoblast (E) Trophoblast
(C) Epiblast
Type I collagen described in Question 10 belongs to which subfamily of collagens? (A) Anchoring fibril-forming collagens (B) Fibril-associated collagens (C) Fibril-forming collagens (D) Network-forming collagens (E) Transmembrane collagens
(C) Fibril-forming collagens
A soft tissue biopsy is examined in the pathology department. Normal adipocytes are examined at high magnification (shown in the image). The clear space that has pushed the cytoplasm and nucleus to the periphery of these cells is best described by which of the following terms? (A) Endosome (B) Granule (C) Inclusion (D) Vacuole (E) Vesicle
(C) Inclusion
Which of the following proteins contributes to the structural matrix that anchors chromatin to the nuclear membrane during interphase of the cell cycle? (A) Desmin (B) Keratin (C) Lamin (D) Perlecan (E) Vimentin
(C) Lamin
A 23-year-old woman complains of recurrent bone pain and increasing abdominal girth. Physical examination reveals enlargement of the patient's liver and spleen (hepatosplenomegaly). A spleen biopsy reveals large macrophages, with a fibrillar appearance reminiscent of "wrinkled tissue paper" (shown in the image). The patient is subsequently diagnosed with Gaucher disease. She carries mutations in the genes for glucocerebrosidase. Without this hydrolytic enzyme, glucocerebroside accumulates within which of the following cellular organelles? (A) Autophagic vacuoles (B) Endoplasmic reticulum (C) Lysosomes (D) Mitochondria (E) Peroxisomes
(C) Lysosomes
An 85-year-old woman with Alzheimer disease dies in her sleep. At autopsy, hepatocytes are noted to contain golden cytoplasmic granules that do not stain with Prussian blue (shown in the image). This "wearand-tear" pigment of aging (lipofuscin) accumulates primarily within which of the following cellular organelles? (A) Endosomes (B) Golgi apparatus (C) Lysosomes (D) Peroxisomes (E) Vacuoles
(C) Lysosomes
A 44-year-old woman presents with a 2-week history of fever and painful joints. Physical examination shows skin pigmentation, glossitis (inflammation of tongue), and generalized lymphadenopathy. The patient has lost 9 kg (20 lb) over the past 6 months. She reports that her stools are pale and foul smelling. Biopsy of the small intestine is shown in the image. Identify the cells indicated by the arrows. (A) Eosinophils (B) Fibroblasts (C) Macrophages (D) Mast cells (E) Plasma cells
(C) Macrophages
Which of the following bone marrow-derived cells is typically found within open spaces formed by the extra- cellular matrix fibers described in Question 5? These cells are believed to play an important role in anticancer immune surveillance. (A) Lymphocytes (B) Mast cells (C) Macrophages (D) Neutrophils (E) Plasma cells
(C) Macrophages
A 2-year-old girl with itchy skin and respiratory distress is brought to the emergency room by her parents 30 minutes after eating peanut butter cookies. On physical examina- tion, the patient shows flushing and swelling of her lips and eyelids. Hives are present over her face and arms. Vital signs are blood pressure 90/40 mm Hg and pulse 100 per minute. Which of the following inflammatory cells is primarily responsible for the development of increased vascular permeability in this patient with a severe peanut allergy? (A) Eosinophils (B) Macrophages (C) Mast cells (D) Neutrophils (E) Plasma cells
(C) Mast cells
A 38-year-old woman delivers a stillborn neonate with craniofacial abnormalities at 24 weeks gestation. A section of fetal skull is examined by light microscopy (shown in the image). Which of the following types of connective tissue best describes this autopsy specimen? (A) Dense irregular connective tissue (B) Hyaline cartilage (C) Mesenchyme (D) Nonmineralized bone (E) Red bone marrow
(C) Mesenchyme
You are invited to give a seminar on the molecular mechanisms of lineage formation and cell differentiation. During the seminar, you are asked to list the primary germ layers of the embryo and discuss their derivatives. Blood vessels and hematopoietic stem cells originate from which of the following tissues/structures during embryogenesis? (A) Ectoderm (B) Endoderm (C) Mesoderm (D) Neural crest (E) Notochord
(C) Mesoderm
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? (A) Endocrine (B) Goblet (C) Mucous (D) Paracrine (E) Serous
(C) Mucous
You are studying the differentiation of epithelial cells lining the intestinal mucosa and identify a common stem cell for the secretory lineage that gives rise to Paneth cells, enterocytes, and goblet cells. Which of the following terms describes the developmental potential of these gastrointestinal stem cells? (A) Embryonic (B) Metaplastic (C) Multipotent (D) Nullipotent (E) Pluripotent
(C) Multipotent
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) Catalase (B) Cytochrome (C) Na/K ATPase (D) Perforin (E) Superoxide dismutase
(C) Na/K ATPase
The adipocytes described in Question 30 are surrounded and supported by a network that is composed chiefly of which of the following fibers? (A) Collagen (B) Elastic (C) Reticular (D) Skeletal muscle (E) Smooth muscle
(C) Reticular fibers
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. (A) Pseudostratified cuboidal (B) Simple columnar (C) Simple cuboidal (D) Simple squamous (E) Stratified columnar
(C) Simple cuboidal
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) Pseudostratified columnar (B) Stratified columnar (C) Stratified cuboidal (D) Stratified squamous (E) Transitional
(C) Stratified cuboidal
The genes for green fluorescent protein and tubulin are spliced, and the fusion protein is expressed in a myoblast cell line. The distribution of microtubules is monitored by confocal fluorescence microscopy (shown in the image). During mitosis, these cytoskeletal proteins are reorganized to coordinate chromosome separation. Which of the following organelles is the principal microtubule- organizing center in these myoblasts? (A) Astral fibers (B) Basal body (C) Centromeres (D) Centrosomes (E) Kinetochores
(D) Centrosomes
Electron microscopic examination of the epithelial cells described in Question 18 reveals basolateral membrane infoldings (interdigitations). What is the most likely function of this membrane specialization? (A) Endocytosis (B) Enzyme secretion (C) Exocytosis (D) Fluid transport (E) Immune surveillance
(D) Fluid transport
The parents of a 3-year-old boy are concerned that their son shows signs of physical and mental retardation. After a series of physical and laboratory examinations, the child is diagnosed with Hurler syndrome. This rare genetic disease is caused by disordered degradation and abnormal accumulation of which of the following con- nective tissue structural components? (A) Collagen fibers (B) Elastic fibers (C) Glycoproteins (D) Glycosaminoglycans (E) Proteoglycan core proteins
(D) Glycosaminoglycans
Which of the following connective tissue components binds the most water and regulates the crucial biological functions of the viscous and highly hydrated ground substance described in Question 16? (A) Elastic fibers (B) Fibroblasts (C) Glycoproteins (D) Glycosaminoglycans (E) Proteoglycan core proteins
(D) Glycosaminoglycans
A 17-year-old boy presents with yellow and red-crusted lesions over his face of 5-day duration. He is a mem- ber of the high school wrestling team and has a recent history of intermittent low-grade fever. Skin cultures arepositive for Streptococcus pyogenes. Spread of this bacte- rial infection within the patient's dermis may occur if the intrinsic viscosity of dermal connective tissue is altered by infection. Which of the following connective tis- sue components determines the viscosity of connective tissue and provides a protective barrier that limits the spread of deep-seeded bacterial infections in the skin? (A) Collagen type I fibers (B) Elastic fibers (C) Fibroblast (D) Ground substance (E) Reticular (type III collagen) fibers
(D) Ground substance
A 28-year-old marine complains of gingivitis, skin hem- orrhages, multiple infections, and poor wound healing. Laboratory studies suggest vitamin C deficiency (scurvy). Lack of vitamin C in this patient primarily affects which of the following essential steps in collagen fibrillogenesis? (A) Cleavage of uncoiled collagen propeptides (B) Formation of tropocollagen fibrils (C) Galactosylation of hydroxylysine residues (D) Hydroxylation of proline and lysine residues (E) Secretion of procollagen into extracellular space
(D) Hydroxylation of proline and lysine residues
Fluorescent fusion proteins are used to monitor the distribution of organelles in a myoblast cell line. The distribution of mitochondria and microfilaments is examined by confocal fluorescence microscopy (shown in the image). In this composite image, DNA is colored blue, microfilaments are colored green, and mitochondria are colored red. Which of the following cell adhesion proteins forms anchoring junctions that link actin microfilaments to adhesive glycoproteins on the surface of the culture dish? (A) Cadherins (B) Cloudins (C) Connexins (D) Integrins (E) Selectins
(D) Integrins
A 42-year-old woman presents with increasing abdominal girth and yellow discoloration of her skin and sclera. Physical examination reveals hepatomegaly and evidence of liver failure (jaundice). A Prussian blue stain of a liver biopsy is shown in the image. This stain identifies which of the following elements? (A) Calcium (B) Cobalt (C) Copper (D) Iron (E) Potassium
(D) Iron
An obese, 18-year-old man (BMI = 32 kg/m2 ) presents with questions regarding his weight. The patient admits to an unusually strong appetite and uncontrolled food intake. His behavior may be related to decreased serum concentration of which of the following hormones? (A) Cholecystokinin (B) Ghrelin (C) Glucagon (D) Leptin (E) Melatonin
(D) Leptin
For the biopsy described in Question 1, which of the following types of connective tissue is found directly beneath the basophilic surface epithelium? This tissue is highly cellular and contains capillary loops that provide nutrients and oxygen to the overlying epithelium. (A) Adipose tissue (B) Dense irregular connective tissue (C) Elastic connective tissue (D) Loose connective tissue (E) Reticular connective tissue
(D) Loose connective tissue
In the image shown for Question 25, which of the following types of connective tissue best describes the cellular layer that lies below the simple columnar, lining epithelium? (A) Adipose tissue (B) Dense irregular connective tissue (C) Elastic connective tissue (D) Loose connective tissue (E) Reticular connective tissue
(D) Loose connective tissue
A small muscular artery is examined in the pathology department. Smooth muscle fibers in the tunica media appear red, whereas collagen bundles in the tunica adventitia appear blue (shown in the image). This slide was most likely colored using which of the following histochemical stains? (A) Aldehyde fuchsin (B) Hematoxylin and eosin (C) Luxol fast blue/cresyl violet (D) Masson trichrome (E) Periodic acid-Schiff
(D) Masson trichrome
The principal investigator of your laboratory asks you whether pluripotent ES cells can differentiate into neural crest cells or primordial germ cells. You suggest that cellular and molecular markers would help you answer that question. Markers for which of the following cells could be used to monitor neural crest cell differentiation in vitro? (A) Cardiac myocytes (B) Hepatocytes (C) Keratinocytes (D) Melanocytes (E) Enterocytes
(D) Melanocytes
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)? (A) Ectoderm (B) Endoderm (C) Intermediate mesoderm (D) Mesenchyme (E) Somitic mesoderm
(D) Mesenchyme
Hepatocytes from a liver biopsy are examined by electron microscopy. Identify the elongated organelles shown in the image. (A) Endoplasmic reticulum (B) Golgi apparatus (C) Lysosomes (D) Mitochondria (E) Peroxisomes
(D) Mitochondria
A digital slide of a sympathetic chain ganglion is examined in the histology laboratory. Large multipolar neurons are surrounded by nerve fibers and connective tissue (shown in the image). Identify the dark basophilic region within the nucleus of these ganglion cells. (A) Basal body (B) Centrosome (C) Golgi apparatus (D) Nucleolus (E) Peroxisome
(D) Nucleolus
A kidney biopsy from a 44-year-old man is examined by electron microscopy. The nucleus of an endothelial cell exhibits a peripheral ring of dark-stained chromatin (arrow, shown in the image). Which of the following best describes the functional significance of the dark-stained ring of marginal chromatin observed in this electron micrograph? (A) DNA replication center (B) Kinetochore complex assembly (C) Nucleosome assembly (D) Organization of inactive chromatin (E) Ribosomal RNA biosynthesis
(D) Organization of inactive chromatin
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) Aldehyde fuchsin (B) Hematoxylin and eosin (C) Luxol fast blue/cresyl violet (D) Periodic acid-Schiff (E) Trypan blue
(D) Periodic acid-Schiff
During fibrillogenesis of type I collagen, the triple helix of the procollagen molecule is formed at which of the following locations? (A) Extracellular space (B) Golgi apparatus (C) Nucleus (D) Rough endoplasmic reticulum (E) Secretory vesicles
(D) Rough endoplasmic reticulum
You are involved in a translational research project to develop small-molecule inhibitors of pepsin secretion by chief cells in the stomach mucosa. Chief cells store precursor enzymes within zymogen granules. By electron microscopy, these "protein factory" cells would most likely show an abundance of which of the following intracellular organelles? (A) Centrosomes (B) Endosomes (C) Phagolysosomes (D) Rough endoplasmic reticulum (E) Smooth endoplasmic reticulum
(D) Rough endoplasmic reticulum
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) Pseudostratified cuboidal (B) Simple columnar (C) Simple cuboidal (D) Simple squamous (E) Stratified columnar
(D) Simple squamous
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). (A) Basal lamina (B) Glycocalyx (C) Lamina propria (D) Striated brush border (E) Terminal web
(D) Striated brush border
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) Actin (B) Desmin (C) Keratin (D) Tubulin (E) Vimentin
(D) Tubulin
A spinal cord smear preparation is obtained at autopsy and stained with Luxol fast blue/cresyl violet. The large octopus-like cells on this slide are multipolar motor neurons (shown in the image). What protein forms intracellular tracts that deliver organelles and vesicles to distant nerve terminals via anterograde axonal transport? (A) Actin (B) Clathrin (C) Lamin (D) Tubulin (E) Ubiquitin
(D) Tubulin
Thick Camper fascia from the abdomen of a 72-year-old man is examined at autopsy (shown in the image). Which of the following best describes histologic features of this tissue? (A) Multilocular adipose tissue with cellular hyperplasia (B) Multilocular adipose tissue with cellular hypertrophy (C) Unilocular adipose tissue with cellular hyperplasia (D) Unilocular adipose tissue with cellular hypertrophy (E) Unilocular adipose tissue with cellular metaplasia
(D) Unilocular adipose tissue with cellular hypertrophy
What intracellular protein complex links microtubules of the spindle apparatus to sister chromatids during mitosis and meiosis? (A) Astral fibers (B) Centrioles (C) Centromere (D) Centrosome (E) Kinetochore
(E) Kinetochore
A skin biopsy is examined at a double-headed microscope. The surgical pathologist directs your attention to waxy/lipid material filling the cytoplasm of secretory cells forming a sebaceous gland (shown in the image). Secretion of this waxy material to the pilosebaceous canal involves programmed cell death (apoptosis). Which of the following cytologic features provides evidence of apoptosis in this gland? (A) Aggregation of intermediate filaments (B) Disaggregation of polyribosomes (C) Membrane blebs (D) Mitochondrial swelling (E) Nuclear pyknosis
(E) Nuclear pyknosis
Which of the following cellular processes describes the uptake of extracellular fluids and small particles by the cell described in Question 18? (A) Autophagy (B) Exocytosis (C) Involution (D) Phagocytosis (E) Pinocytosis
(E) Pinocytosis
A 48-year-old man is admitted to the hospital with a fever of 38°C (103°F), night sweats, persistent cough, and prolonged diarrhea. Stool culture reveals the presence of acid-fast bacilli that are identified as Mycobacterium avium-intracellulare. Immune responses to the pathogen are known to involve IgA antibodies that are secreted into the lumen of the small intestine. This immunoglobulin is produced and secreted by which of the following bone marrow-derived cells? (A) Eosinophils (B) Macrophages (C) Mast cells (D) Neutrophils (E) Plasma cells
(E) Plasma cells
A biopsy of the small intestine is sectioned and stained with H&E (shown in the image). Identify the cell indicated by the arrow. (A) Eosinophil (B) Macrophage (C) Mast cell (D) Neutrophil (E) Plasma cell
(E) Plasma cells
A biopsy of an axillary lymph node from the patient described in Question 3 is examined by light micros- copy. In this silver-stained section (shown in the image), the irregular black lines indicated by the arrows represent which of the following stromal connective tissue components? (A) Elastic fibers (B) Fibrillin microfibrils (C) Fibronectin glycoproteins (D) Heparin sulfate proteoglycans (E) Reticular fibers
(E) Reticular fibers
A sample of adrenal cortex obtained 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). Cells of the zone fasciculata appear washed out and "spongy" due to an accumulation of cholesterol and other precursors for steroid hormone biosynthesis. Electron microscopic examination of these "steroid factory" cells would be expected to show an abundance of which of the following organelles? (A) Autophagic vacuoles (B) Dense-core secretory granules (C) Golgi apparatus (D) Rough endoplasmic reticulum (E) Smooth endoplasmic reticulum
(E) Smooth endoplasmic reticulum
A portion of the small intestine is collected at autopsy, and sections are stained with periodic acid-Schiff (PAS) and counterstained with hematoxylin. The mucosa of the intestine is examined by light microscopy (shown in the image). PAS is particularly useful for identifying which of the following biological materials? (A) Collagens (B) Lipids (C) Nucleic acids (D) Proteins (E) Sugars
(E) Sugars
You attend a national meeting on regenerative medicine. One of the talks focuses on cellular senescence and cancer. Reactivation of the gene for which of the following nuclear proteins may enable some cancer cells to escape cellular senescence, continue to proliferate, and maintain genomic stability? (A) DNA helicase (B) Lamin A (C) Oct 4 transcription factor (D) Rb tumor suppressor protein (E) Telomerase
(E) Telomerase
You are investigating maternal factors that regulate thecell cycle during early development. A mouse embryo is flushed from the uterine tube, treated with acid Tyrode solution to remove its zona pellucida, and examined by phase microscopy (shown in the image). The embryo exhibits a cleavage furrow and appears to be undergoing cytokinesis. These events take place during what phase of mitosis? (A) Anaphase (B) Interphase (C) Metaphase (D) Prophase (E) Telophase
(E) Telophase
The right lower limb of a 6-year-old boy becomes swol- len and enlarged following a visit to South Africa. He is diagnosed with lymphatic filariasis. The patient's soft tissue swelling (edema) is caused by an accumulation of which of the following connective tissue components? (A) Collagen fibers (B) Glycoproteins (C) Glycosaminoglycans (D) Proteoglycans (E) Tissue fluid
(E) Tissue fluid
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) Pseudostratified columnar (B) Stratified columnar (C) Stratified cuboidal (D) Stratified squamous (E) Transitional
(E) Transitional
Hematopoietic stem cells are cultured in vitro at 37°C in the presence of recombinant erythropoietin. A photomicrograph of a typical "burst-forming unit" committed to the erythrocyte pathway of differentiation is shown in the image. Which of the following histochemical stains can be used as a "vital dye" to distinguish viable from nonviable cells in your cell culture? (A) Aldehyde fuchsin (B) Hematoxylin and eosin (C) Luxol fast blue/cresyl violet (D) Periodic acid-Schiff (E) Trypan blue
(E) Trypan blue
A cervical biopsy is obtained from a 42-year-old woman with a history of abnormal Pap smears. The tissue is tested for human papillomavirus (HPV) by in situ hybridization using cDNA probes. Evidence of HPV viral genome is detected in cells in the cervical biopsy (dark blue spots, shown in the image). The patient is told that she is at increased risk for the development of cervical cancer. She asks you to elaborate. You explain that HPV encodes an early gene (E6) that activates a cellular protein that, in turn, accelerates the degradation of the p53 tumor suppressor protein. Name the protein that is activated by HPV E6. (A) β-Catenin (B) Cathepsin (C) Glucuronyl transferase (D) GTP-activating protein (E) Ubiquitin ligase
(E) Ubiquitin ligase
Which of the following terms best describes the PASpositive goblet cells identified in the image for Question 20? (A) Multicellular endocrine glands (B) Multicellular exocrine mucous glands (C) Multicellular exocrine serous glands (D) Unicellular enteroendocrine glands (E) Unicellular exocrine mucous glands
(E) Unicellular exocrine mucous glands
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) Gap junctions (B) Hemidesmosomes (C) Macula adherens (desmosomes) (D) Zonula adherens (E) Zonula occludens
(E) Zonula occludens
