GastritisParietal Cells, GastricH(+)-K(+)-Exchanging ATPaseGastritis, AtrophicAutoimmune DiseasesThymectomyAnemia, PerniciousGastric MucosaGastrinsAchlorhydriaHelicobacter pyloriHelicobacter InfectionsIntrinsic FactorAutoantibodiesStomachMice, Inbred BALB CAutoantigensLymphopeniaPyloric AntrumGastritis, HypertrophicCD4-Positive T-LymphocytesMetaplasiaT-Lymphocytes, RegulatoryGastroscopyPepsinogen AImmunoglobulin GStomach NeoplasmsBile RefluxDisease Models, AnimalMice, Inbred C57BLStomach UlcerPeptic UlcerPepsinogen CStomach DiseasesDuodenal UlcerHelicobacter felisHelicobacter heilmanniiChronic DiseaseDuodenitisDyspepsiaHelicobacterBiopsyUreasePepsinogensPostgastrectomy SyndromesGastric JuicePrecancerous ConditionsEndoscopy, GastrointestinalCampylobacterAtrophyAcinonyx