Immune System
Polymorphonuclear leukocytes (or PMNs)

are a type of phagocyte that can engulf and kill bacteria
can be attracted to the site of an infection following activation of complement
All of these
are derived from bone marrow stem cells

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Immune System
The role of the M cell is to

pass bacteria or virus to underlying macrophages for processing and presentation of antigen
trap virus in mucus and prevent entry
induce apoptosis in virus-infected small intestinal epithelia cells
they use their cilia to propel mucus out of the small intestine

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