Download Nissl bodies correspond to which of the following cytoplasmic

Nissl bodies correspond to which of the following cytoplasmic organelles?
A. Golgi apparatus
B. Mitochondria
C. Nucleoli
D. Rough endoplasmic reticulum
E. Smooth endoplasmic reticulum
Explanation:
The correct answer is D. This is a straightforward question relating to the definition of Nissl
bodies. Rough endoplasmic reticulum present in neurons are called Nissl bodies. They stain
intensely with basic dyes and are found in the cell body and proximal dendrites, but not in the
axon hillock or axon.
A premature infant develops progressive difficulty breathing over the first few days of life. Deficient
surfactant synthesis by which of the following cell types may have contributed to the baby's
respiratory problems?
A. Alveolar capillary endothelial cells
B. Bronchial mucous cells
C. Bronchial respiratory epithelium
D. Type I pneumocytes
E. Type II pneumocytes
Explanation:
The correct answer is E. The child has neonatal respiratory distress syndrome (hyaline membrane
disease). This condition is caused by the inability of the immature lungs to synthesize
adequate amounts of surfactant. Surfactant, which reduces surface tension, helps keep alveoli
dry and aids in expansion of the lungs, is synthesized by type II pneumocytes.
Alveolar capillary endothelial cells (choice A) are important in maintaining the capillary
structure and permitting flow of gases into and out of the blood stream.
Bronchial mucous cells (choice B) produce the usually thin (in healthy individuals) coat of
mucus that lines the bronchi.
The ciliated bronchial respiratory epithelium (choice C) is responsible for moving the dust
coated mucus layer out of the bronchi.
Type I pneumocytes (choice D) are the squamous cells that line alveoli and permit easy gas
exchange. These cells tend to be immature (and thick) in premature infants, but do not produce
surfactant.
A surgical pathology specimen from a 24-year-old woman seen at a reproductive medicine clinic
demonstrates a ciliated columnar epithelium. From which of the following locations in the
female genital tract was the biopsy obtained?
A. Cervix
B. Endometrium
C. Fallopian tube
D. Ovary
E. Vagina
Explanation:
The correct answer is C. The fallopian tube is the only structure in the female genital tract
with a ciliated columnar epithelium; the beating of the cilia helps move the egg into the
uterus. This fact is also sometimes clinically helpful since dilated and deformed fallopian
tubes can be microscopically distinguished from cystic ovarian tumors by the presence of the
cilia.
The cervix (choice A) and vagina (choice E) are lined by squamous epithelium.
The endometrium (choice B) is lined by columnar epithelium (although a few ciliated cells may
be present).
The covering of the ovary (choice D) is cuboidal epithelium, and cysts within the ovary can be
lined by cuboidal or non-ciliated columnar epithelium.
A 40-year-old women presents with a several year history of progressive abdominal colic and
constipation. Colonic biopsy stained with hematoxylin and eosin demonstrates deposition of a
pink acellular material in the submucosa and around blood vessels. When sections from this
biopsy are stained with Congo red, the acellular material exhibits green birefringence. The
birefringence is thought to be most closely related to which of the following protein
properties?
A. Ability to bind to oxygen
B. Beta-pleated sheet tertiary structure
C. Electrophoretic mobility
D. Hydroxyproline content
E. Molecular weight
Explanation:
The correct answer is B. The patient has amyloidosis, which can be present in the manner illustrated.
Originally, it was thought that amyloid represented a single protein. However, as the various
settings in which amyloidosis occurs were further explored, it was discovered that a variety of
clearly distinct proteins could produce the material. Eventually, it was observed that what
these diverse proteins had in common was a beta-pleated sheet tertiary structure that
apparently is reflected in the apple-green birefringence. None of the other properties are
thought to contribute to birefringence when viewed with polarized light.
The ability to bind oxygen (choice A) is important to hemoglobin.
Electrophoretic mobility (choice C) is used to separate serum proteins.
Hydroxyproline content (choice D) is important to collagen structure.
Molecular weight (choice E) is a basic protein property.
A 5-year-old boy falls off his bike and fractures his humerus. He is taken to the emergency room, and
the bone is set by one of the emergency room physicians. Which of the following is responsible
for producing the majority of the new bone that will reunite the two fragments?
A. Cancellous bone
B. Cartilage
C. Compact bone
D. Marrow
E. Periosteum
Explanation:
The correct answer is E. When the periosteum is torn during a fracture, it supplies cells that
develop into osteoblasts and are the major producers of the new bone that reunites the two
ends. Heterotopic ossification (bone formed outside the regular bone) can occur as a
complication of fracture if some of the osteoblastic cells are misdirected into adjacent
tissues.
Preexisting cancellous bone (choice A) and compact bone (choice C) are not the major source of
osteoblasts that form the new bone.
Cartilage (choice B) and marrow (choice D) do not contribute to new bone formation after fracture.
Which of the following sites contains striated muscle that is not under voluntary control?
A. Bladder
B. Colon
C. Esophagus
D. Gallbladder
E. Stomach
Explanation:
The correct answer is C. Striated (skeletal) muscle not under voluntary control is an unusual
feature of the upper third of the esophagus. The middle third of the esophagus contains roughly
half striated and half smooth muscle; the lower third contains only smooth muscle. All the
other structures listed in the answer choices contain smooth muscle.
A 27-year-old male presents to the doctor with complaints of "heartburn" and painful, sour-tasting acid
reflux that has not been alleviated by over-the-counter medications. An endoscopic exam is
performed and a biopsy of the distal esophagus is taken. Microscopic examination of the tissue
shows normal tissue without pathologic changes. What type of mucosa is normal for the distal
esophagus?
A. Ciliated, columnar epithelium
B. Keratinized, stratified, squamous epithelium
C. Non-ciliated, columnar epithelium
D. Non-keratinized, simple, squamous epithelium
E. Non-keratinized, stratified, squamous epithelium
F. Pseudostratified, columnar epithelium
Explanation:
The correct answer is E. The esophagus is covered by non-keratinized, stratified, squamous
epithelium for its entire length. Heartburn is usually a sign of gastric regurgitation of the
acidic contents in the lower esophagus (acid reflux disease). Acid reflux disease is a serious
problem that may be associated with a precancerous condition (Barrett's esophagus).
Histologic examination of normal skin demonstrates small numbers of perivascular cells, with darkly
stained ovoid nuclei and granular cytoplasm on hematoxylin and eosin staining. The cells
demonstrate metachromasia of the cytoplasm when stained with Giemsa stain. Which of the
following products would these cells be most likely to secrete?
A. Bradykinin
B. Complement factor 3a
C. Histamine
D. Interleukin 2
E. Nitric oxide
Explanation:
The correct answer is C. The cells in question are mast cells, which play an important role in
IgE-mediated allergic responses. They are a normal (minor) constituent of dermal skin and are
most definitely identified with stains, such as the Giemsa stain, that highlight the
granularity of their cytoplasm (mast cells are closely related to blood basophils). Mast cells
secrete histamine, serotonin, many leukotrienes, and platelet aggregating factor (PAF). Their
histamine secretion after IgE stimulation helps to trigger the acute inflammatory part of the
allergic response.
Bradykinin (choice A) is a nonapeptide found in the plasma. It is a potent vasodilator and
stimulates pain receptors.
Complement factor 3a (choice B) is a plasma protein that induces vascular leakage as part of the acute
inflammatory response.
Interleukin 2 (choice D) is secreted by lymphocytes and augments the immune response.
Nitric oxide (choice E) is released by macrophages and endothelium. It causes vasodilation and
cytotoxicity.
A 35-year-old male presents to the urologist for an infertility evaluation. A biopsy of his testis is
performed to check sperm production and maturation. A microscopic section reveals only a few
germ cells near the basal lamina in the seminiferous tubule. Which of the following cells is
the germ cell closest to the basal lamina in the seminiferous tubule?
A. Primary spermatocyte
B. Secondary spermatocyte
C. Spermatid
D. Spermatogonia
E. Spermatozoa
Explanation:
The correct answer is D. Maturation of germ cells (spermatogenesis) within the seminiferous
tubules occurs in a concentric pattern with the less mature spermatogonia near the basal lamina
and the mature forms near the tubule center. Spermatogonia are 2N cells and mature into larger
primary spermatocytes (4N) (choice A). These mature into secondary spermatocytes (2N) (choice
B), and finally into spermatids (1N) (choice C). Spermatids undergo spermiogenesis to become
mature spermatozoa (choice E). Acrosomes form from the Golgi apparatus and a flagellum forms
from microtubules. Unneeded organelles are shed. The seminiferous tubules of a reproductive-age
male should exhibit all stages of maturation, with mature flagellated sperm in their centers.
Brunner's glands secrete an alkaline product that helps achieve optimal pH for the activity of
pancreatic enzymes. Where are these glands located?
A. At the base of villi throughout the small intestine
B. In the epithelium of the ampulla of Vater
C. In the mucosa and submucosa of the jejunum
D. In the submucosa of the duodenum
E. In the submucosa of the ileum
Explanation:
The correct answer is D. Brunner's glands are located in the submucosa of the duodenum. These
glands are connected to the intestinal lumen by ducts that open into certain crypts. They
secrete an alkaline product that protects the duodenal mucosa from the acidic chyme and helps
achieve optimal pH for pancreatic enzymes.
Note that if you did not recall the location of Brunner's glands, the question's description of
their function allowed you to deduce it, based on your knowledge of the anatomy of the small
intestine. You should have immediately ruled out choices C and E because they are too far from
the pancreas. Choices B and D would therefore remain as the best possible answers because of
their proximity to the pancreas. If you remembered the structure and function of the ampulla of
Vater, you were left with the correct answer.
Let's review some other key features of intestinal histology by way of the wrong answer choices.
The small intestinal villi (choice A) are outgrowths of the mucosa into the lumen. Their
epithelium contains columnar absorptive cells and goblet cells (produce acid glycoproteins that
protect and lubricate the lining of the intestine). Near the base of each villus, there are
tubular glands called crypts whose lining is continuous with the simple columnar epithelium of
the villus. The crypts include Paneth cells, which produce acidophilic cytoplasmic granules
containing bacteriocidal enzymes. The lamina propria of the small intestine penetrates the core
of the villi and is composed of blood vessels, lymphatics, fibroblasts, and smooth muscle
cells.
The ampulla of Vater (choice B) receives bile from the common bile duct and the main pancreatic duct,
delivering it to the duodenum through the major duodenal papilla.
The mucosa and submucosa of the jejunum (choice C) are both included in the permanent folds
called the plica circulares.
The submucosa of the ileum (choice E) is the home of Peyer's patches, which are large
aggregates of lymphoid nodules.
Routine chest x-ray of a worker in a tuberculosis sanitorium reveals a focal calcification initially
thought to be a lung lesion. However, x-rays taken in different views establish that the
abnormal calcification involves a structure other than the lung. Physiologic calcification of
which of the following structures would most likely cause the radiologic shadow?
A. Aorta
B. Costal cartilage
C. Intercostal arteries
D. Intercostal veins
E. Vena cava
Explanation:
The correct answer is B. Focal calcification of hyaline cartilage is common and may initially
be troublesome in that it may suggest a pathologic rather than physiologic process.
Calcification of the hyaline cartilage of the costal cartilages is notorious for producing
"phantom" lung lesions.
The aorta (choice A) can develop calcified atheromatous plaques, but these would not be
localized to the chest wall.
Calcification of the intercostal vessels (choices C and D) or vena cava (choice E) would be unusual.
Most fascia of the body that attach to bones attach by which of the following mechanisms?
A. Blending with the covering periosteum
B. Inserting deeply into the cancellous bone
C. Inserting deeply into the cartilage
D. Inserting deeply into the diaphysis
E. Inserting deeply into the marrow
Explanation:
The correct answer is A. Fascial straps (retinacula) and fascial coverings of muscles or muscle groups
characteristically attach to nearby bones by blending with the covering periosteum. No deep
attachments are usually made by fascia.
Cancellous bone (choice B) is spongy bone, which is usually found in marrow, and is not the
site for fascial attachment.
Fascia do not usually attach to cartilage (choice C).
Fascia attaches to bony shafts, or diaphyses (choice D), superficially via the periosteum.
Fascia do not penetrate the bone to reach the marrow (choice E).
Microscopic examination of a PAS-stained histological section through a Graafian follicle demonstrates a
bright reddish-pink, acellular ring around the ovum. Which of the following terms most
accurately describes this ring?
A. Corona radiata
B. Cumulus oophorus
C. Theca externa
D. Theca interna
E. Zona pellucida
Explanation:
The correct answer is E. The ring described is the zona pellucida, which surrounds the ovum. The zona
pellucida is rich in polysaccharides and glycoproteins and consequently stains brightly pink or
red with PAS stain. Binding of the sperm cell membrane to the zona pellucida triggers the
acrosome reaction, during which acrosomal enzymes are released that digest the zona pellucida,
allowing the spermatozoon to contact and fuse with the ovum cell membrane.
The follicular cells immediately outside the zona pellucida form the corona radiata (choice A).
The larger cumulus oophorus (choice B) is the hill of follicular cells that surrounds the ovum.
The theca interna (choice D) and externa (choice C) are formed from the connective tissue
surrounding the follicle.
A 24-year-old delivery driver is involved in an accident and sustains a wide abrasion over his left
elbow. The abrasion results in the total loss of epidermis over a large area of his left arm,
but one month later, the abrasion has healed, with regrowth of the epidermis. Which of the
following mechanisms accounts for the restoration of the epidermis over the abraded area?
A. Growth of epidermis from hair follicles and sweat glands in the dermis
B. Migration of endothelial cells from newly grown capillaries
C. Transformation of dermal fibroblasts into epidermal cells
D. Transformation of macrophages into epidermal cells
E. Transformation of melanocytes into epidermal cells
Explanation:
The correct answer is A. The dermis contains skin appendages (e.g., hair follicles) that
contain epithelial stem cells. In the process of healing a large area where the epidermis has
been lost, but the dermis is intact, re-epithelialization occurs by ingrowth of epidermal cells
from the underlying skin appendages, as well as from the intact epidermis along the wound
edges.
None of the other cell types are known to directly contribute to the regeneration of epidermis
over abraded skin.
Damage to which of the following structures might produce hair cell loss?
A. Basilar membrane
B. Organ of Corti
C. Reissner's membrane
D. Scala tympani
E. Scala vestibuli
Explanation:
The correct answer is B. The structure of the cochlea is complex. The organ of Corti contains
hair cells from the cochlear branch of the vestibulocochlear nerve (CN VIII). These cells rest
on the basilar membrane (choice A), which separates the scala tympani (choice D) from the scala
media. The hairs of the hair cells are embedded in the tectorial membrane, and movement of the
basilar membrane below the cells tends to bend the hairs, which generates action potentials by
the hair cells. The tectorial membrane that lies on the hair cells does not form a boundary
between the different scala; the membrane separating the scala media from the scala vestibuli
(choice E) is Reissner's (vestibular) membrane (choice C).
In the adult, neurons are an example of which of the following?
A. Continuously dividing cells
B. Labile cells
C. Permanent cells
D. Quiescent cells
E. Stable cells
Explanation:
The correct answer is C. Permanent (non-dividing) cells have left the cell cycle and can no
longer undergo mitotic division. Examples that are usually cited include neurons and cardiac
myocytes. In contrast, labile (continuously dividing) cells, such as those that form most
epithelial linings, continue to proliferate throughout life, and stable (quiescent) cells, such
as in the liver and other body organs, proliferate in response to stimuli such as injury.
Examples of labile (continuously dividing) cells (choices A and B) include the epithelia of the
body surface, gastrointestinal tract, and urinary tract.
Examples of stable (quiescent) cells (choices D and E) include the cells of the glandular
organs of the body.
Which of the following hormones is secreted by anterior pituitary cells that stain with acidic dyes?
A. ACTH
B. FSH
C. LH
D. Prolactin
E. TSH
Explanation:
The correct answer is D. The cells of the anterior pituitary can be classified as chromophils
(love dyes) or chromophobes (do not stain with dyes). The chromophils can be further divided
into acidophils (stain with acidic dyes) and basophils (stain with basic dyes). The acidophils
include the somatotropes, which secrete growth hormone, and the mammotropes, which secrete
prolactin. The basophils include the corticotropes, which secrete ACTH (choice A), the
gonadotropes, which secrete FSH and LH (choices B and C), and the thyrotropes, which
secrete TSH (choice E).
A researcher is examining the distribution of an ion channel protein in the kidney. She incubates slices
of kidney tissue in a dilute solution of a specific antibody directed against the protein, then
uses the immunoperoxidase method to localize the ion channel proteins. She notes the presence
of brown pigment in a population of epithelial cells, which on closer examination, have a brush
border. The researcher concludes that the protein is probably present in cells of the
A. collecting duct
B. deep portion of loop of Henle
C. distal convoluted tubule
D. glomerulus
E. proximal convoluted tubule
Explanation:
The correct answer is E. The immunoperoxidase method uses horseradish peroxidase to produce a visible
pigment when a specific antibody binds to antigenic sites in the tissue. Binding of the
antibody to the epithelial cells indicates that the protein in question is being expressed by
those cells. The positive immunoperoxidase results obtained here suggests that the channel
protein is expressed in proximal convoluted tubular epithelium, since this is the only site in
the kidney at which the epithelial cells have a "brush border." The brush border is made of
microvilli, which enhance the proximal tubules' ability to reabsorb plasma constituents
filtered at the glomeruli.
Which of the following is found in the respiratory zone of the lung?
A. Goblet cells
B. Main bronchi
C. Mucous cells
D. Terminal bronchioles
E. Type I epithelial cells
Explanation:
The correct answer is E. There are two zones in the lung—the conducting zone (where there
is no gas exchange) and the respiratory zone (where there is gas exchange). Of all of the
structures listed, only Type I epithelial cells are located in the respiratory zone. Type I
epithelial cells are the primary structural cell of the alveolar wall. Type II epithelial
cells, also located in the alveoli, are the cells that produce surfactant.
Goblet cells (choice A), which are mucus-secreting cells, are present in the conducting airways.
The main bronchi (choice B) are part of the conducting airways.
Mucous cells (choice C), which are mucus-secreting cells, are present in the conducting airways.
Terminal bronchioles (choice D) are the most distal part of the conducting airways. Respiratory
bronchioles, which are just distal to the terminal bronchioles, are part of the respiratory
zone. These two types of bronchioles can be differentiated from each other by whether they have
alveoli budding from their walls. Respiratory bronchioles have alveoli, terminal bronchioles do
not.
An AIDS patient develops symptoms of pneumonia, and Pneumocystis carinii is suspected as the causative
organism. Bronchial lavage is performed. Which of the following stains would be most helpful in
demonstrating the organism's cysts on slides made from the lavage fluid?
A. Alcian blue
B. Hematoxylin and eosin
C. Methenamine silver
D. Prussian blue
E. Trichrome stain
Explanation:
The correct answer is C. The appropriate stain is methenamine silver, and the requisition slip
when submitting the wash fluid should have a reference to either Pneumocystis or methenamine
silver, since routine hematoxylin and eosin does not adequately demonstrate the organisms. The
cysts, when stained with methenamine silver, have a characteristic cup or boat shape; the
trophozoites are difficult to demonstrate without electron microscopy. It is also worth knowing
that sputum samples are not nearly as effective as bronchial washes in demonstrating the
organisms.
Alcian blue (choice A) is good for demonstrating mucopolysaccharides.
Hematoxylin and eosin (choice B) is the routine tissue stain used in pathology laboratories.
Prussian blue (choice D) is good for demonstrating iron.
Trichrome stain (choice E) is good for distinguishing fibrous tissue from nerve and muscle.
A gastric biopsy is taken from a 42-year-old man. As the pathologist inspects the specimen, he observes
numerous, normal cuboidal-to-columnar cells with apical membrane-bound secretion granules in
the gastric glands. From which area of the stomach was the biopsy most likely taken?
A. Cardiac region
B. Columns of Morgagni
C. Fundic region
D. Greater omentum
E. Pyloric region
Explanation:
The correct answer is C. The pathologist saw normal chief cells, which are abundant in the body
and fundus of the stomach. Chief cells secrete pepsinogen, which is stored in apical membranebound granules. The body and fundus of the stomach contain high concentrations of four other
types of cells in the epithelium. The parietal (oxyntic) cells are large, pyramidal, and
acidophilic with central nuclei (look like a "fried egg"). They make and secrete HCl. The
mucous neck cells secrete mucus and appear clear. The enteroendocrine cells have affinity for
silver stains and exhibit a positive chromaffin reaction; these cells synthesize amines,
polypeptides, or proteins.
The cardiac region (choice A) is a narrow, circular band at the transition between the
esophagus and stomach, consisting of shallow gastric pits and mucous glands. It does not
normally contain an abundance of chief cells.
The columns of Morgagni (choice B) are found in the rectum, not in the stomach. These are
mucous membrane infoldings in the submucosa of the proximal anal canal. They would not contain chief
cells.
The greater omentum (choice D) is a four-layered fold of peritoneum that hangs from the greater
curvature of the stomach and attaches to the transverse colon. It would not contain chief cells.
The pyloric region (choice E) has deep gastric pits into which tubular glands open. The
predominant secretion is mucus. It does not normally contain an abundance of chief cells.
Note that in this question you could have automatically eliminated choices B and D, since they
are not gastric structures. If nothing else, you would have improved your guessing odds to 33%.
Observation of a hematoxylin and eosin-stained microscope slide reveals that the nuclei are blue. What
is the basis for this observation?
A. Eosin binds to carbohydrates
B. Eosin binds to lipids
C. Eosin binds to nucleic acids
D. Hematoxylin binds to lipids
E. Hematoxylin binds to nucleic acids
Explanation:
The correct answer is E. Blue hematoxylin binds to polyanions such as RNA and DNA. Nuclei
contain large amounts of DNA and RNA, and they are consequently almost always blue. The nuclei of
dysplastic and cancerous cells are often enlarged and hyperchromatic (e.g., darker blue) compared to
normal cells of similar cell lines, because these altered cells often have extra DNA (are aneuploid)
and/or RNA (are metabolically active).
Pink eosin binds relatively nonselectively to cellular components, particularly proteins.
Cytoplasm of different cell lines can be pink, purple, or blue, depending principally on the
number of ribosomes in the cytoplasm. Consequently, blue-tinged cytoplasm tends to suggest high
synthetic activity (e.g., abundant ribosomes).
In which of the following organs are fenestrated endothelial cells common?
A. Heart
B. Liver
C. Lungs
D. Pancreas
E. Stomach
Explanation:
The correct answer is B. Fenestrated ("windowed") endothelial cells, which permit free flow of
serum across the endothelium, are an unusual feature of the hepatic sinusoids. They are not
seen in the other organs listed.
Which of the following tissues normally has the highest percentage of mucus-secreting cells?
A. Esophageal mucosa
B. Oral mucosa
C. Parotid gland
D. Sublingual gland
E. Submandibular gland
Explanation:
The correct answer is D. Salivary glands can contain predominantly serous cells, predominantly
mucous cells, or both in their acini. As you proceed from the midline laterally, acini in the
sublingual gland are almost pure mucous cells, while acini in the submandibular gland (choice
E) contain a mixture of serous and mucous cells. Acini in the parotid gland (choice C) are
mostly pure serous cells.
The esophageal mucosa (choice A) and the oral mucosa (choice B) are squamous epithelia that do
not form acini.
Microscopic examination of a section of a normal young adult ovary reveals large numbers of unusually
large cells surrounded by a single layer of flat epithelial cells. In which phase of the cell
cycle are these cells arrested?
A. Diplotene stage of the 1st meiotic division
B. Diplotene stage of the 2nd meiotic division
C. Metaphase stage of mitosis
D. Prophase stage of mitosis
E. Prophase stage of the 2nd meiotic division
Explanation:
The correct answer is A. The cells described are the primordial eggs, which remain stopped in
the diplotene stage of the first meiotic division from before birth until fertilization, a
period which may be 40 or more years.
Choices B and E are incorrect because the oocytes are stopped in the first, not second meiotic
division.
Choices C and D are incorrect because the cells described are oocytes and are not in mitosis.
A 32-year-old renal transplant patient who had been doing well on azathioprine and prednisone abruptly
develops fever, chills, and cough productive of rust-colored sputum. A fiberoptic biopsy is
performed that shows tissue destruction and areas suspicious for fungus. Which of the following
special stains would best demonstrate fungal forms?
A. Gram's stain
B. Hematoxylin and eosin
C. Masson's trichrome
D. Methenamine silver
E. Ziehl-Neelsen stain
Explanation:
The correct answer is D. The methenamine silver stain is a silver impregnation stain that is
good for detecting both fungal organisms and hyphae. They appear black against a blue-green background.
Gram's stain (choice A) is used in the general classification of bacteria. The Gram's stain is
picked up by the bacterial cell wall. Gram's iodine with safranine counterstain is most commonly used.
Hematoxylin and eosin (choice B) is the standard pathology stain. As in the case above, it shows areas
suspicious for fungi, but special stains are needed to confirm it.
Masson's trichrome (choice C) is a connective tissue stain. It stains the supporting tissues,
especially collagen. The stain produces 3 colors: blue nuclei, green connective tissue, and red blood.
The Ziehl-Neelsen stain (choice E), or acid fast stain, is used for certain acid fast organisms
such as mycobacteria. The stain is taken up by cell walls and remains in the cell wall despite
washing with acid. The organisms appear red against a blue background.
Infections in hyaline cartilage typically destroy the cartilage because
A. cartilage contains chondroitin sulfate
B. cartilage contains collagen
C. cartilage is not innervated
D. cartilage is relatively avascular
E. cartilage tends to become calcified
Explanation:
The correct answer is D. Hyaline cartilage contains very few, sparsely distributed, small
blood vessels. The tissue consequently is very vulnerable to infection because the immune
system (white cells and serum with clotting factors and antibodies) cannot access the
cartilage in an efficient fashion.
Chondroitin sulfate (choice A) is an important constituent of cartilage that can be attacked
by bacteria, but this is not the cause of uncontrollable infections in the cartilage, because
if the infection is controlled, chondrocytes will continue to synthesize chondroitin.
Collagen (choice B) is present in cartilage, but does not predispose the cartilage for
uncontrollable infection.
Collagen is not innervated (choice C), but this does not contribute to the development of
uncontrollable infection.
The tendency of cartilage to undergo calcification (choice E), even when not acting as the
site of ossification, does not predispose for uncontrollable infection.
Following a fracture of the humerus, an adult patient has a biopsy of the healing area. Which of the
following types of bone will the biopsy most likely show?
A. Cancellous
B. Compact
C. Spongy
D. Trabecular
E. Woven
Explanation:
The correct answer is E. Bone is formed by type I collagen fibers, ground substance, and
hydroxyapatite crystals. The collagen is oriented in a layered or lamellar fashion. It can be
parallel (trabecular bone and periosteum) or concentric (Haversian system). When bone is formed
quickly, as in a healing fracture site, metabolic bone disease, or tumor, the collagen is
randomly oriented and is called woven bone.
Compact bone (choice B) is the dense calcified external part of the bone. It is lamellar bone.
Cancellous (choice A), spongy (choice C) and trabecular bone (choice D) are all synonymous
terms for the thinner network of bone within the cortex. These are also lamellar bone.
A 36-year-old Asian male complains of difficulty swallowing. Esophagoscopy reveals a polypoid mass that
is subsequently biopsied. In addition to tumor cells, the esophageal biopsy show normal smooth muscle
and striated muscle in the same section. Which portion of the esophagus was the source of this biopsy?
A. Lower esophageal sphincter
B. Lower third of the esophagus
C. Middle third of the esophagus
D. Upper esophageal sphincter
E. Upper third of the esophagus
Explanation:
The correct answer is C. The middle third of the esophagus contains both striated and smooth muscle.
The lower third (choice B) of the esophagus, including the lower esophageal sphincter (choice
A) contain only smooth muscle.
Some authors identify the cricopharyngeus muscle as an upper esophageal sphincter (choice D)
despite the fact that unlike a true sphincter, this muscle does not completely encircle the
esophagus. The cricopharyngeus is composed exclusively of skeletal muscle, therefore, the
biopsy could not have been from this area of the esophagus.
The muscularis of the upper third of the esophagus (choice E) is composed entirely of striated muscle.
A pathologist is looking at a histological section of aorta stained to demonstrate the many wavy fibers
that provide the aorta with the flexibility to stretch and then return to its original shape.
These fibers are also found in substantial numbers in the
A. biceps muscle
B. liver
C. mesentery
D. spleen
E. vocal cords
Explanation:
The correct answer is E. The fibers are elastic fibers. You should remember three specific
sites where these are found: large arteries (particularly the aorta), vocal cords, and
ligamenta flava (which connect the vertebrae). Small amounts of elastic tissue are also found
in skin, and to a much lesser degree in other tissues.
Elastic tissue is not found in muscle (choice A) or mesentery (choice C).
Elastic tissue is not found in substantial amounts in the liver (choice B) or spleen (choice D).