Uptake of orally administered polystyrene latex and poly(D,L-lactic/glycolic acid) microspheres into intestinal lymphoid tissues in chickens

Fluorescein-labeled microspheres were orally administered to chickens and t heir distribution in intestinal lymphoid tissues was investigated. Polystyr ene latex microspheres were observed in Peyer's patches, and also in the Me ckel's diverticulum and the jejunum. Their density, however, seemed to be l ower than that in Peyer's patches, Microspheres were rarely observed in the other intestinal tissues examined, including the bursa of Fabricius. Of no te is that, although microspheres were present in the lumen, few, if any, w ere observed in the lamina propria of the caecal tonsil and caecum. Polysty rene latex microspheres of diameter 2.0 mu m or 4.5 mu m were also observed in Peyer's patches, but their density seemed to be lower as compared with the 0.75 mu m microspheres. Poly(D,L-lactic/glycolic acid) (PLGA) microsphe res were prepared using PLGAs of various molecular weights (MW) and their u ptake into Peyer's patches was compared. Microspheres prepared with PLGA of average MW of 20 000 were not taken up into Peyer's patches, but those pre pared with PLGA of average MW of 61 000 or 99 800 were taken up into Peyer' s patches. (C) 1999 Elsevier Science B.V. All rights reserved.