Antigen-trapping cells in Peyer's patches of the rat.

Peyer's patches (PP) of rats were studied with immunocytochemical, enzyme cytochemical, and electron microscopic techniques. Special attention was paid to the non-lymphoid antigen-trapping cells. Follicular dendritic cells, morphologically comparable to those present in spleen and lymph nodes, were found in the germinal centers of PP. Ia-positive cells with the morphological characteristics of interdigitating cells were seen in the interfollicular area. Thus, both types of antigen-presenting cells, characteristic for B- and T-cell areas, respectively, were present in PP.