Patterns of Migration of Labelled Blood Lymphocyte Subpopulations: Evidence for Two Types of Peyer’s Patch in the Young Pig

Abstract

Although in many ways apparently conventional, the lymphoid system of the pig differs from that of other species in some important respects: The lymph node is structurally inverted with a peculiar medulla and its efferent lymph is almost devoid of lymphocytes since recirculating lymphocytes emigrate directly into veins. Moreover a large proportion of blood lymphocytes (~40% and 4000/mm³) in young pigs are Null T-dependent cells which apparently do not recirculate^1,2Although there have been careful studies of the incidence of lymphocytes in different lymphoid organs (see ²) quantitative data are lacking on the migration of labelled blood lymphocytes to the lymphoid tissues and their changes with time. This paper using ⁵¹Cr- and FITC-labelling provides evidence of major heterogeneity of tissue and lymphocyte population behaviour in blood lymphocyte migration including evidence for two different types of Peyer’s patch.