ILEAL PEYERS-PATCHES IN PIGS - INTERCELLULAR AND LYMPHATIC PATHWAYS

Background: The lymphatics of Peyer's patches disseminate immunologica l information from the gut and thus play a key role in protection of t he body against environmental pathogens. The aim of this project was t o describe the lymphatic pathways of these Peyer's patches in pigs, an d the mucosal intercellular spaces which lead to these lymphatics. Met hods: Heal tissue from living or freshly killed pigs was examined by l ight microscopy or electron microscopy, or was injected with Mercer (C L-B-2, Japan Vilene Hospital, Tokyo) for scanning electron microscopy of corrosion casts. Results: Intercellular fluid between intestinal ep ithelial cells passes through pores in the basal lamina to mix with th at in the intercellular spaces and prelymphatic intercellular channels of the lamina propria and follicle domes. From there, lymph enters la cteals in the villi, or a branching network of vessels within the lami na propria. Small lymphatics penetrate the muscularis mucosae and are continuous with (1) lymphatic vessels which pass directly to the deep submucosa between follicles, or (2) lymphatic sinuses which lie adjace nt to the follicles, This differs from the situation in sheep and rabb its. Basal lymphatics beneath the follicles convey lymph to vessels wh ich leave the surface at the serosa. Conclusion: The differences in th e structure and arrangement of the lymphatics of Peyer's patches betwe en pigs, sheep, and rabbits will require further investigation to dete rmine if such variation between species has an effect on the distribut ion of immune products to effector sites. (C) 1994 Wiley-Liss, Inc.