Ontogeny of Peyer's Patches and Immunoglobulin-Containing Cells in Pigs

Abstract

Abstract The embryonic development of intestinal lymphoid tissue and immunoglobulin-containing cells (µ-, γ- and light chain determinants) was examined in 55 porcine fetuses. Lymphoid cells in a characteristic follicular distribution were found in Peyer's patches as early as 50 days of gestation, but detection of Peyer's patches from 50 to beyond 70 days of gestation required microscopic examination of serial sections of the intestines. The size of the intestinal lymphoid follicles steadily increased during gestation, but cortico-medullary division was not observed until after birth. IgM-containing cells were first seen in 55-day spleens and were followed by IgG-containing cells in the thymus 10 to 15 days later. These observations are interpreted as support for the hypothesis that the lymphoid follicles in Peyer's patches are mammalian bursa-equivalent sites.