62
UNIT 2
Basic Tissues
Figure 4-3A.
Connective tissue cells in lamina propria.
Modif
ed H&E,
×
680; inset approximately
3
1,200
An example oF cells in loose connective tissue is shown.
Fibro-
blasts
are the predominant cells in connective tissue, where they
produce procollagen and other components oF the extracellu-
lar matrix (±ig. 4-7A).
Plasma cells
arise From activated B lym-
phocytes and are responsible For producing antibodies.
Mast
cells
have small, ovoid nuclei and contain numerous cytoplas-
mic granules. When stained with toluidine blue, these granules
are metachromatically stained and appear purple (±ig. 4-4A).
Mast cells are involved in allergic reactions.
Eosinophils
arise
From hematopoietic stem cells and are generally character-
ized by bilobed nuclei and numerous eosinophilic cytoplasmic
granules; they are attracted to sites oF infl ammation by leuko-
cyte chemotactic Factors where they may deFend against a par-
asitic inFection or moderate an allergic reaction.
Neutrophils
are phagocytes oF bacteria; each cell has a multilobed nucleus
and some granules in its cytoplasm. ±or more details on
leukocytes, see Chapter 8, “Blood and Hemopoiesis.”
Mast cell
Neutrophil
Eosinophil
Plasma cells
GZ
Fibroblast
Lymphocyte
Eosinophil
Plasma cells
Macrophage
Fibroblast
Macrophage
A
D. Cui
Fibroblast
Plasma cell
Mast cell
Eosinophil
B
lymphocyte
Neutrophil
Adipocyte
Macrophage
Collagen fiber
Elastic fiber
B
Figure 4-3B.
A representation of the cells found in loose
connective tissue.
(These cells are not drawn to scale.)
(1)
Fibroblasts
are spindle-shaped cells with ovoid or elliptical
nuclei and irregular cytoplasmic extensions. (2)
Macrophages
have irregular nuclei. The cytoplasm contains many lysosomes;
cell size may vary depending on the level oF phagocytic activ-
ity. (3)
Adipocytes
contain large lipid droplets, and their nuclei
are pushed to the periphery. They are usually present in aggre-
gate (see ±ig. 4-18). (4)
Mast cells
have centrally located ovoid
nuclei and numerous granules in their cytoplasm. (5)
Plasma
cells
have eccentric nuclei with peripheral distribution oF het-
erochromatin (clock Face) within the nuclei; a clear Golgi area
is present within the cytoplasm. (6)
Eosinophils
have bilobed
nuclei and coarse cytoplasmic granules. (7)
Neutrophils
and
lymphocytes
are also Found in connective tissue, and their
numbers may increase in cases oF infl ammation.
CLINICAL CORRELATION
Figure 4-3C.
Anaphylaxis.
Anaphylaxis
is an allergic reaction that may range
From mild to severe and is characterized by increased
numbers oF
basophils
and
mast cells
,
dilated capil-
laries
, and exudates in the loose connective tissue.
Symptoms include
urticaria (hives)
,
pruritus (itching)
,
ushing, shortness oF breath, and shock. Anaphylaxis
results From the activation and release oF
histamine
and
infl ammatory mediators
From
mast cells
and
basophils
.
Some drugs can cause IgE-mediated anaphylaxis and
non–IgE-mediated anaphylactoid reactions. Previous
exposure to a suspect antigen is required For the For-
mation oF
IgE,
but anaphylactoid reactions can occur
even upon f rst contact in rare cases. Some antibiotics,
such as penicillin, can cause severe allergic reactions.
Immediate administration oF epinephrine, antihista-
mine, and corticosteroids is the f rst option oF emer-
gency treatment, along with endotracheal intubation
to prevent the throat From swelling shut, iF necessary.
D. Cui
Collagen fiber
Dilated capillary
Active mast cell
Active basophil
Dilated blood vessel
C
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