1
The photomicrograph shows a section of synovium from the knee joint of a patient with rheumatoid
arthritis (RA).
Which of the following are the most abundant cells in the inflammatory infiltrate?
A. Eosinophils
B. Langhans type giant cells
C. Lymphocytes and plasma cells
D. Neutrophils
E. Type A and B synovial cells
Explanation:
The correct answer is C. Lymphocytes and plasma cells aggregate near and around blood vessels
(perivascular
accumulation) in this example of chronic inflammation of the synovium. Lymphocytes have dark nuclei
with little
visible cytoplasm. Plasma cells are larger with a distinct cytoplasm and an eccentric nucleus. The
synovial lining is
thickened from its normal 1-2 layers. Note that you did not have to be able to recognize lymphocytes
and plasma
cells in the photomicrograph to answer this question. Because RA is associated with a chronic
inflammatory
infiltrate, lymphocytes and plasma cells must be the correct answer.
Eosinophils (choice A) are not evident here and do not seem to play a role in RA.
Langhans type giant cells (choice B), or multinucleated histiocytes, are not evident here but may appear
during the
later stages of RA.
Neutrophils (choice D) are not evident here; they are instead associated with acute inflammation.
Type A and B synovial cells (choice E) are the two cell types of the synovial lining. They increase in
number but are
not the cells of the perivascular infiltrate.
4
The leukocyte pictured above stains intensely with acidic dyes such as eosin. Which of the following
substances is
contained in the crystalline core of the granule at the arrow?
A. Lactoferrin
B. Major basic protein
C. Myeloperoxidase
D. Histamine
E. Tartrate-resistant acid phosphatase
Explanation:
The correct answer is B. The cell pictured is an eosinophil, a member of the granulocytic lineage of
white blood
cells. The crystalline core of the granule contains a protein called the major basic protein, which
appears to function
in the destruction of parasites. Major basic protein also has deleterious effects on epithelial cells in
patients with
asthmatic reactions. The light component around the dense crystalline core contains products such as
histaminase,
arylsulfatase, and other enzymes.
Lactoferrin (choice A) is found in the specific granules of the neutrophil. It inhibits the growth of
bacteria by
interfering with iron metabolism.
Myeloperoxidase (choice C) is found in the azurophilic (large) granule of the neutrophil. This enzyme
is also
destructive to bacteria, destroying their cell walls.
Histamine (choice D) is produced by the basophil and the mast cell. The histaminase of the eosinophil
regulates the
inflammatory reaction of these two cell types.
Tartrate-resistant acid phosphatase (choice E) is a marker for hairy cell leukemia, a neoplasm of the B
lymphocyte
line.
5
Axons found around the area indicated by the arrow in the figure above are myelinated by
A. astrocytes
B. dorsal root ganglion cells
C. microglia
D. oligodendrocytes
E. Schwann cells
Explanation:
The correct answer is D. The arrow is in the fasciculus cuneatus, a tract in the white matter of the spinal
cord.
Therefore, it is within the central nervous system (CNS). Myelin in the central nervous system is
formed by
oligodendrocytes. Each oligodendrocyte myelinates several axons.
Astrocytes (choice A) are stellate appearing cells possessing branching processes that associate with pia
mater,
neurons, and endothelial cells within the CNS. While they may provide a secondary component of the
blood-brain
barrier (tight junctions account for the primary barrier), one of their main functions is to modulate the
molecular
composition of extracellular fluid in the CNS. They do not produce myelin.
Dorsal root ganglion cells (choice B) are pseudounipolar neurons that provide sensory input to the
spinal cord.
Their axons may be myelinated, but they do not form the myelin.
Microglia (choice C) are part of the mononuclear phagocyte system, being derived from monocytes.
They are
phagocytic and do not produce myelin.
Schwann cells (choice E) form myelin in the peripheral nervous system. A Schwann cell forms myelin
around a
single axon.
6
The black line drawn across this photomicrograph of a seminiferous tubule represents the line of
demarcation
between which of the following ?
Immediately above
Immediately below
A. Cells undergoing meiosis II
Cells undergoing meiosis I
B. Cells undergoing spermatocytogenesis
Cells undergoing spermiogenesis
C. Cells undergoing spermatogenesis
Vascular system
D. Cells undergoing spermiogenesis
Myoid cells
Explanation:
The correct answer is C. The line represents the blood-testis barrier. Spermatogenesis occurs in three
phases:
spermatocytogenesis, meiosis, and spermiogenesis. Progeny of spermatogonia formed during
spermatocytogenesis move from below the line (basal compartment) to above the line (adluminal
compartment).
Cells commence meiosis I below the line and then move through the barrier before chromosomal
crossing over
occurs during prophase of meiosis I. Tight junctions of Sertoli cells (which have prominent nucleoli)
seal this barrier.
Meiosis I continues in the adluminal compartment, followed by meiosis II and differentiation
(spermiogenesis).
Myoid, or contractile, cells are located outside of the basal lamina, beneath the spermatogonia.
8
The cell in the center of the electron micrograph above is important in wound healing and plays a role
in the
pathological process underlying Dupuytren's contracture. Which of the following cell types is depicted?
A. Endothelial cell
B. Myoepithelial cell
C. Myofibroblast
D. Pericyte
E. Smooth muscle cell
Explanation:
The correct answer is C. The cell is spindle-shaped like a fibroblast; however, the difference is that the
cytoplasm
contains several bundles of microfilaments. These bundles are parallel to the long axis of the cell and
are seen
immediately beneath the cell membrane and within the cytoplasm. Densities, comparable to Z-lines,
can be seen
along some of these bundles. The microfilaments are responsible for the contractile properties of this
cell. These
contractile properties, in addition to the cell's ability to link with collagen, function in wound closure in
the healing
process. Dupuytren's contracture, which is a contracture of the palmar fascia, is caused by interaction
of these
cells with collagen fibrils of the fascia.
The endothelial cell (choice A) lines vessels. There are no vessels in the photomicrograph.
The myoepithelial cell (choice B) contains microfilaments and is contractile. However, it is closely
associated with
glandular epithelium (not apparent here).
The pericyte (choice D) is a multipotential connective tissue cell found near or around blood vessels,
but it does
not contain microfilament bundles such as these. There are no vessels apparent in the photomicrograph.
The smooth muscle cell (choice E) is joined by junctions to other smooth muscle cells, arranged in
bundles.
Microfilaments make up most of the cytoplasm of such cells, with the nucleus in a central location.
10
The modified structures at the border of the epithelium shown above are immotile in a 23-year-old
patient. Which of
the following would be a consequence of this lack of motility?
A. Implantation failure
B. Kartagener's syndrome
C. Malabsorption syndrome
D. Reduction in number of disaccharidases
E. Uptake and digestion of spermatid residual bodies
Explanation:
The correct answer is B. The border modification consists of cilia on the surface of pseudostratified
columnar
epithelium. Cilia are shorter than stereocilia and usually appear bent or wavy in sections. Kartagener's
syndrome is
one type of immotile cilia syndrome in which the dynein arms of microtubules are missing or
defective. Thus, cilia
cannot move properly and all functions associated with them are affected (mucous sweeping or ciliary
elevator
functioning, sperm motility, embryonic cell movement, etc.). The result is infertility, situs inversus,
bronchiectasis
and/or sinusitis.
Implantation (choice A) is not affected in patients with Kartagener's syndrome. The fertilized ovum
can still reach
the endometrium and implantation can occur. Also, this is not a section of the uterine tube; the uterine
tube has a
simple columnar epithelium with peg cells (secretory) and ciliated cells.
The border modification consists of cilia, not microvilli and the specimen is not a section of the
intestine, therefore
malabsorption (choice C) is incorrect. Both the small and large intestine have a simple columnar
epithelium with
microvilli. Microvilli are upright and irregular and resemble a "flat top" haircut across the top of cells.
Disaccharidases (choice D) are present in the cell membrane of microvilli. Deficiencies in digestion
occur with the
loss of microvilli.
Uptake and digestion of residual bodies of spermatids (choice E) occurs in the epididymis. Even
though the
epididymis has pseudostratified columnar epithelium, the epithelial border contains stereocilia: long
microvilli which
may be two to three times the length of cilia.
17
Which of the following occurs at the darkly stained band indicated by the arrow?
A. Acrosome reaction
B. Aromatase acts on testosterone
C. Capacitation
D. Implantation receptors are exhibited
E. Meiosis is resumed
Explanation:
The correct answer is A. The photomicrograph depicts an oocyte. The zona pellucida at the arrow is
similar to a thick
basal lamina and is composed of glycoproteins that bind to the cell membrane of the sperm head. This
binding
triggers the acrosome reaction, which involves fusion of the acrosomal membrane with the overlying
sperm
membrane. The acrosomal enzymes are released and digest the zona pellucida, allowing the
spermatozoon to make
contact and fuse with the ovum cell membrane.
The enzyme aromatase (choice B) is found in the granulosa cells, which surround the oocyte and the
follicular wall.
Testosterone, produced by the theca cells, diffuses through the basal lamina of the follicle and is
converted to
estradiol by aromatase.
Capacitation (choice C) refers to changes that occur in the spermatozoa during their transit through the
female
reproductive tract. These changes occur in the oviducts and the uterus. Sperm become motile in the
epididymis.
The oocyte divides many times as it moves toward the uterus, the zona pellucida disappearing. A portion
of these
cells will exhibit implantation receptors (choice D) and become an implantation site for the cell mass in
the uterine
wall.
Meiosis is resumed (choice E) in the oocyte shortly before ovulation. The nucleus of the oocyte can be
seen in the
center. The oocyte and the surrounding granulosa cells make up this structure, known as an antral or
secondary
follicle.