Question

Pathogens can enter the body by many routes and set up infections anywhere, but antigen and lymphocytes will eventually encounter each other in the peripheral lymphoid organs. Lymphocytes are continually recirculating through these tissues, to which antigen is also carried from all sites of infection and where it is displayed by specialized cells. Specialized structures collect antigen from the epithelial surfaces of the gastrointestinal tract. What is the most important and highly organized of these tissues?

Spleen
Peyer's patches
Thymus
Bone marrow
Primary lymphoid organ

Answer 1

The most important and highly organized tissues collecting antigens from the gastrointestinal tract's epithelial surfaces are Peyer's patches. They contain antigen-presenting cells like dendritic cells and play a pivotal role in immune surveillance and response.

Step-by-step explanation:

The most important and highly organized of the tissues that collect antigen from the epithelial surfaces of the gastrointestinal tract are known as Peyer's patches. These structures are part of the mucosa-associated lymphoid tissue (MALT) and play a critical role in the immune surveillance of the intestinal lumen and in facilitating the immune response to pathogens encountered along the gastrointestinal tract.

Peyer's patches contain antigen-presenting cells such as dendritic cells, which take up antigens and present them to T cells and B cells within the patches. This action leads to the activation of lymphocytes and the development of an effective immune response against pathogens. Moreover, Peyer's patches are considered secondary lymphoid organs where mature lymphocytes congregate to mount immune responses.