Role of M cells and macrophages in the entrance of Mycobacterium paratuberculosis into domes of ileal Peyer's patches in calves.
Ligated ileal loops of calves were inoculated with live and heat-killed Mycobacterium paratuberculosis and were examined by light and electron microscopy. At 5 hours after inoculation, acid-fast bacilli were in subepithelial macrophages, but not in M cells covering domes. At 20 hours, more than 50 acid-fast bacilli per cross section were in subepithelial macrophages in domes. Both living and heat-killed bacilli passed into domes. Addition of anti-M. paratuberculosis bovine serum to the inoculum enhanced entry of bacteria into domes. By electron microscopy, intact bacilli with electron-transparent zones (peribacillary spaces) were in the supranuclear cytoplasm of M cells at 20 hours. M cells also contained vacuoles, including electron-dense material interpreted as degraded bacilli. Subepithelial and intraepithelial macrophages contained bacilli and degraded bacterial material in phagosomes. These results suggest that calf ileal M cells take up bacilli, and that subepithelial and intraepithelial macrophages secondarily accept bacilli or bacterial debris which are expelled from M cells.
Momotani
E
E
US Department of Agriculture, National Animal Disease Center, Ames, IA.
Whipple
D L
DL
Thiermann
A B
AB
Cheville
N F
NF
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000382:microbiology*; D007082:Ileum / Q000382:microbiology / Q000648:ultrastructure; D008264:Macrophages / Q000382:microbiology* / Q000648:ultrastructure; D008854:Microscopy, Electron; D009161:Mycobacterium / Q000276:immunology / Q000502:physiology* / Q000648:ultrastructure; D010283:Paratuberculosis / Q000382:microbiology*; D010581:Peyer's Patches / Q000382:microbiology* / Q000648:ultrastructure; D010587:Phagocytosis