Phagocytosis and transcytosis by the follicle-associated epithelium of the ileal Peyer's patch in calves.

Latex beads, 250 and 610 nm in diameter, and parapox virus isolated from ecthyma in sheep, were injected into intestinal loops containing either jejunal or ileal Peyer's patches (PP) of 3-4 week old calves. Uptake of latex and parapox virus was restricted to the ileal PP, 30-60 min after injection. The latex beads seemed to be embraced by thin surface protrusions extending from the concentric folds of the follicle-associated epithelial cells (FAE) of the ileal PP. Both latex and virus were internalized into cytoplasmic vacuoles. Some of the vacuoles containing virus showed reaction for acid phosphatase. The latex beads and virus were shed to the intercellular spaces of the FAE. The exocytosis appeared to occur through specialized indentations of the lateral plasma membrane where the production of 50 nm membrane-bounded particles by budding off from the lateral plasma membrane was a prominent phenomenon.