At the intestine: inner antigens are processed at ILFs while outer antigens are processed in Peyer patches (hypothesis)

At the intestine: inner antigens are processed at ILFs while outer antigens are processed in Peyer patches.

ILF: inducible lymph follicle
https://www.ncbi.nlm.nih.gov/pubmed/12759424

"In contrast to the spleen, LNs and PPs, ILFs are inducible structures developed after birth due to the presence of external stimuli43"
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5015111/

The MRC marginal reticular cells develop here at the inducible ILF of the intestine.

pericytes in the gut
https://www.ncbi.nlm.nih.gov/pubmed/30937864

Peyer patches have the FRC fibroblast reticular cells.

Brain macrophages : pericytes
https://www.ncbi.nlm.nih.gov/pubmed/10611494

MHC2 expression by pericytes
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5844098/

pericytes and the BBB
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4292164/

peyer patch lacking mice had no IgA only IgG from ILFs
https://www.jimmunol.org/content/jimmunol/173/2/762.full.pdf

Remember the lymph structure and the separate zones for inner and outer antigens:

Then the spleen's separate zones:

Now looking for the MRC and the FRC we find very separate zones in the intestine: