To clarify the rule of fetal antigen presentation cells in the histogenesis of GALT, expressions of cell membrane antigens and MHC class II mRNA were examined in gut-associated lymphoid tissue of normal fatal calves. The formation of jejunal and ileal Payer’s patches were initially found at 150 days of fetal age, and two different types of dendritic cells, germinal center dendritic cells and follicular dendritic cells, were identified based on the distribution in the fetal tissues and the profile of cell membrane antigens. Furthermore, gene expression of MHC class II was detected in fetal mesenteric lymph nodes by a RT-PCR method. Overall, antigen presentation cells may play an important rule in the formation of GALT in normal fetal calves. (Comparative Pathology Section, Kyushu Research Station TEL +81-99-268-2078)
