Arterial supplies to the spleen in the rat (<i>Rattus norvegicus</i>), degu (<i>Octodon degus</i>), and red-bellied squirrel (<i>Callosciurus erythraeus</i>)

Rodents exhibit diverse morphological and ecological adaptations across species, making them important species for considering the evolutionary background of morphological traits. Although the splenic artery has been described in various rodent species, interspecific comparisons remain difficult due to a lack of uniformity in anatomical descriptions. We therefore traced the ramification patterns of the splenic artery in 15 rats (Rattus norvegicus), 15 degus (Octodon degus), and 10 red-bellied squirrels (Callosciurus erythraeus) using standardized anatomical criteria to enable rigorous interspecific comparisons. In all degus and red-bellied squirrels, the splenic artery was the first independent branch of the celiac artery, while in 73% of rats, the splenic artery emerged as one of the trifurcated branches of the celiac artery. The splenic artery of red-bellied squirrels exhibited the highest average number of divisions before entering the splenic parenchyma compared to the other two species, resulting in the highest average number of splenic branches. Further, the average number of gastric branches, including the short gastric and gastroepiploic arteries, was highest in red-bellied squirrels and lowest in rats. The differences in branching patterns of the splenic artery among three rodent species, as revealed in this study, are expected to provide clues to understanding species differences in ramification patterns of the splenic artery in rodents.