Final answer:
Peyer's patches are specialized clusters of MALT found in the small intestine. They help prevent bacteria from entering the bloodstream and mount immune responses against ingested substances. Peyer's patches contain specialized cells called M cells that sample material from the intestinal lumen.
Step-by-step explanation:
Peyer's patches, which are specialized clusters of MALT (mucosa-associated lymphoid tissue), are found in the small intestine. These patches are most prominent in young people and help prevent bacteria from entering the bloodstream by mounting immune responses against ingested substances. Peyer's patches contain specialized cells called M cells that sample material from the intestinal lumen and transport it to nearby follicles where adaptive immune responses can be triggered.