Figure 1

(A and B) Caecum sections of dogs uninfected (control); (C-H) Caecum sections of dogs naturally infected with L. infantum (A and B) Observe a histological normal picture of the mucosal (lamina propria), muscularis mucosae and submucosal layers, HE (Bars = 62 μm and 32 μm, respectively); (C-H) Symptomatic dog: (C and D) Note an increased number of cells of all gastrointestinal layers, HE (Bars = 62 μm and 32 μm, respectively); (E) Similarly, we can note an increased number of cells of all gastrointestinal layers where a focal cellular exudates (white arrow) where it becomes contiguous into the three gastrointestinal layers (lamina propria, muscularis mucosae and submucosal), HE (Bar = 32 μm); (F and G) Higher magnification of the previous picture: In (F) note parasitized macrophages in the lamina propria (mucosa layer) (white arrows), (Bar = 16 μm) and in (G) observe macrophages loaded with Leishmania in the muscularis mucosae (white arrowheads) and submucosal layers (black arrowheads) (Bar = 16 μm); (H) Multinucleated giant cells (white arrows) or epithelioid cells (black arrowhead) formation can be seen associated to the exudate of mononuclear concentrated in lamina propria (plasma cells - small white arrow, lymphocytes - small black arrow), HE (Bar = 16 μm); LP: Lamina Propria; MM: Muscularis Mucosae; SM: Submucosal; GI: Glands of Intestine Mucosal) and Hematoxilin-Eosin (HE).