Spleen morphology and vascularization in the alligator (Caiman crocodilus yacare – Daudin, 1802)

The Caiman crocodilus yacare is found from northern Argentina to the southern Amazon basin, mainly occurring in Pantanal. Its food consists of fishes and other aquatic vertebrates and invertebrates, such as crabs, winkles, and insects. Its length can reach 3 meters and this species is important because it provides biological control of other animal species, by feeding on weak, old, and ill individuals, unable to escape its attack. A total of 15 alligators were used, young males and females, using histological techniques; injection techniques with Neoprene latex 450 and vinyl acetate; and radiographic techniques to observe particularities of spleen in this species. The organ has a conical shape, being thicker at its cranial end and tapering at its caudal end. Spleen involved the cranial mesenteric artery, which went towards the intestines, from its origin in the celiac artery until its middle third, through the splenic parenchyma in all preparations. Spleen irrigation in the alligator was originated from the celiac artery, through its branch, the cranial mesenteric artery, which branched into splenic arteries, only within this organ. The splenic veins showed up as the cranial, craniomedial, medial, and caudal splenic veins which drain from the splenic capsule to the medullary region, going through the cortical region and going towards the hepatic portal vein. Spleen in the alligator showed no correspondence between the arteries and veins responsible for the vascularization of a certain splenic territory, but one observed arteries irrigating and veins draining particular areas of the splenic parenchyma.