Te neutrophil cytoplasm contains very ﬁne granules (of two
varieties) that are diﬃcult to see (±able 17.2 and
Neutrophils get their name (literally, “neutral-loving”) because
their granules take up both
gether, the two types of granules give the cytoplasm a lilac color.
Some of these granules contain hydrolytic enzymes, and are re-
garded as lysosomes. Others, especially the smaller granules, con-
tain a potent “brew” of antimicrobial proteins, called
Neutrophil nuclei consist of three to six lobes. Because of
this nuclear variability, they are oFen called
) or simply
many shapes of the nucleus).
Neutrophils are our body’s bacteria slayers, and their num-
bers increase explosively during acute bacterial infections such
as meningitis and appendicitis. Neutrophils are chemically at-
tracted to sites of inﬂammation and are active phagocytes. Tey
are especially partial to bacteria and some fungi, and bacterial
killing is promoted by a process called a respiratory burst. In
, the cells metabolize oxygen to produce
potent germ-killer oxidizing substances such as bleach and hy-
drogen peroxide. In addition, defensin-mediated lysis occurs
when the granules containing defensins merge with a microbe-
containing phagosome. Te defensins form peptide “spears”
that pierce holes in the membrane of the ingested “foe.”
o-ﬁlz) account for 2–4%
of all leukocytes and are approximately the size of neutrophils.
Teir nucleus usually resembles an old-fashioned telephone
receiver—it has two lobes connected by a broad band of nuclear
material (±able 17.2 and ²igure 17.10b).
Large, coarse granules that stain from brick red to crim-
son with acid (eosin) dyes pack the cytoplasm. Tese granules
are lysosome-like and ﬁlled with a unique variety of digestive
erythrocytes. Tey characteristically have lobed nuclei (rounded
nuclear masses connected by thinner strands of nuclear mate-
rial), and their membrane-bound cytoplasmic granules stain
quite speciﬁcally with Wright’s stain. ²unctionally, all granulo-
cytes are phagocytes to some degree.
tro-ﬁlz), the most numerous
white blood cells, account for 50–70% of the WBC population.
Neutrophils are about twice as large as erythrocytes.
(All total 4800–
Types and relative percentages of leukocytes in
Erythrocytes comprise nearly 98% of the formed
elements, and leukocytes and platelets together account for the
pale red and blue
Bilobed nucleus, red
(d) Lymphocyte (small):
Large spherical nucleus,
thin rim of pale blue
In each case the leukocytes are surrounded by erythrocytes.
Neutrophils, eosinophils, and basophils have visible cytoplasmic granules; lymphocytes and
monocytes do not. (All 1750
, Wright’s stain.)