Dog, ultrastructural investigation of the fundic mucosa. Figure 2A. Intraluminal H. bizzozeronii-like organism. A tightly coiled spiral-shaped organism without periplasmic fibrils is free-floating in the superficial mucus (TEM, original magnification 8900×). Figure 2B. Intraluminal H. felis-like organism. A tightly coiled spiral-shaped bacteria with periplasmic fibrils is visible in the superficial mucus; multifocal contact between H. felis-like organism and parietal cell microvilli is present (TEM, original magnification 8900×). Figure 2C. Parietal cell containing Helicobacter-like organisms. Multiple sections of Helicobacter-like organisms were localized within a canaliculus (black arrow) (TEM, original magnification 4 400×). Inset: other bacterial sections were unclearly delimited by parietal cell membranes and adjacent to secondary lysosomes (TEM, original magnification 28000×). Figure 2D. High magnification of the cytoplasm of a parietal cell containing two electrondense intracytoplasmic Helicobacter-like organisms (H). In the upper left corner a longitudinal section of an Helicobacter-like organism is surrounded by closely apposed cell membranes which are focally interrupted; in the lower left corner a transverse section of Helicobacter-like organism is partially enclosed in a lysosome (black arrow) (TEM, original magnification 28000×). Figure 2E. Parietal cell with degenerate Helicobacter-like organism characterized by fragmentation and condensation of bacterial contents and dispersion into the parietal cell cytosol (TEM, original magnification 14000×). Figure 2F. Lamina propria of the fundic mucosa. Macrophage in the interstitium between a blood vessel (right) and the basal portion of gastric epithelial cells resting on a basal lamina (upper left corner) containing multiple profiles of well preserved intracytoplasmic Helicobacter-like organisms and electrondense remnants of an entire phagocytized cell, most likely a parietal cell (TEM, original magnification 8900×).