Ontogeny of pig discrete Peyer's patches: Distribution and morphometric analysis

We investigated the development of lymphoid and nonlymphoid cells in discre te Peyer's patches (PP) of the pig using immuno-histology and image analysi s. In newborn piglets discrete PP were mainly populated by CD2+, CD3+ T cel ls, and major histocompatibility complex class II+ cells, many of which wer e of macrophage and dendritic cell lineage. Four days after birth, cells we re localized in defined regions: the follicle; the inter-follicular area an d the dome region. Compartmentalization within the follicle started about 6 days after birth. The first signs of secondary follicles were seen from ab out 14 days. The pig discrete PP attained their mature structure at about 3 weeks after birth. Here we show that despite the demonstration at birth of the cell types that support antigen processing and presentation, PP did no t fully differentiate morphologically until at least this time when antigen can be handled in an efficient manner. Copyright (C) 2001 S.Karger AG, Bas el.