A characteristic which defines a tissue as primary vs.secondary lymphoid tissue is:

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Quizplus · Accepted Answer

The ability of the lymphoid cells to respond to antigens is the characteristic that differentiates primary from secondary lymphoid tissue. Primary lymphoid tissue (such as the bone marrow and thymus) is where lymphoid cells develop and mature, while secondary lymphoid tissue (such as the lymph nodes and spleen) is where mature lymphoid cells encounter and respond to antigens. Therefore, the lymphoid cells in secondary tissue are already activated and are able to mount a response to antigens, while those in primary tissue are not yet activated. The quantity and types of cells in each tissue are not definitive characteristics that differentiate primary from secondary lymphoid tissue.

A Characteristic Which Defines a Tissue as Primary Vs