Vascularization of the small intestine in lesser anteaters, Tamandua tetradactyla (Xenarthra: Myrmecophagidae)

ABSTRACT

The blood supply in the small intestine of seven Tamandua tetradactyla (Linnaeus, 1758), was studied. The method included preparation of the macroscopic collection report, perfusion of the arterial network with water (40ºC), injection of colored latex (Neoprene 650®, 2350-0003 Suvinil® dye), fixation in formaldehyde (10%), and preservation in ethanol (50%). For description and analyzes, dissection under mesoscopic light and photo documentation were performed. The small intestine of T. tetradactyla is irrigated by the cranial mesenteric artery, the ventral visceral branch of the abdominal aorta. The artery emerges from the retroperitoneum and disperses between the layers of the common mesentery, parallel to the caudal mesenteric artery. The primary cranial collateral branches irrigate the pancreas, duodenum, jejunum (13 arteries), ileum (14 vessels), and the cecocolic region. The arteries anastomose with adjacent vessels to form arches. Terminal branches are derived from these peri-intestinal arcs that reach into the intestine through the mesenteric boundary and form capillaries within the lining. The vascular pattern of the lesser anteater differs from those of other previously described vertebrates, but is similar to the pattern found in fetuses of domestic mammals during early intestinal development.