Molecular Biology of the Cell by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter by by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morg

1240 Chapter 22: Stem Cells and Tissue Renewal
neutrophil
platelet
lymphocyte
eosinophil
20 µm
monocyte
red blood cell
(A)
neutrophil
(B)
basophil
(E)
(C)
eosinophil
(D)
monocyte
2 µm
Figure 22–27 White blood cells. (A–D) These electron micrographs show
(A) a neutrophil, (B) a basophil, (C) an eosinophil, and (D) a monocyte.
Electron micrographs of lymphocytes are shown in Figure 24–14. Each
of the cell types shown here has a different function, which is reflected
in the distinctive types of secretory granules and lysosomes it contains.
There is only one nucleus per cell, but it has an irregular lobed shape,
and in (A), (B), and (C) the connections between the lobes are out of the
plane of section. (E) A light micrograph of a blood smear stained with the
Romanowsky stain, which colors the white blood cells strongly. (Courtesy
of Dorothy Bainton.)
Monocytes also give rise to dendritic cells. Like macrophages, dendritic cells
are migratory cells that can ingest foreign substances and organisms, but they do
not have as active an appetite for phagocytosis and instead have a crucial role
as presenters of foreign antigens to lymphocytes to trigger an immune response.
Dendritic cells in the epidermis (called Langerhans cells), for example, ingest foreign
antigens and carry these trophies back from the skin to present to lymphocytes
in lymph nodes.
There are two main classes of lymphocytes, both involved in immune
responses: B lymphocytes make antibodies, while T lymphocytes kill virusinfected
cells and regulate the activities of other white blood cells. In addition,
there are lymphocyte-like cells called natural killer (NK) cells, which kill some
types of tumor cells and virus-infected cells. The production of lymphocytes is a
specialized topic discussed in detail in Chapter 24. Here we concentrate mainly
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on the development of the other blood cells, often referred to collectively as
myeloid cells.
Table 22–1 summarizes the various types of blood cells and their functions.
The Production of Each Type of Blood Cell in the Bone Marrow Is
Individually Controlled
Most white blood cells function in tissues other than the blood; blood simply
transports them to where they are needed. A local infection or injury in any tissue
rapidly attracts white blood cells into the affected region as part of the inflammatory
response, which helps fight the infection or heal the wound (Movie 22.3).
The inflammatory response is complex and is governed by many different signal
molecules produced locally by mast cells, nerve endings, platelets, and white