Anatomical study of the renal excretory system in pigs. A review of its characteristics as compared to its human counterpart

Background: Despite the importance of the pyelocalyceal system in the pig as an experimental model, there is little information about this particular anatomical subject. We determined the morphological characteristics of the renal excretory system in pigs. Materials and methods: This descriptive cross-sectional study evaluated 130 pairs of kidneys of pigs destined to slaughter. The pyelocalyceal system was subjected to injection technique — corrosion by infusion of polyester resin (85% Palatal and 15% Styrene) and subsequent infusion in potassium hydroxide (KOH) for 10 days. The significance level used was p < 0.05. Results: The renal excretory system is characterised by the presence of type A major cranial and caudal calyxes seen in 34.3% of the kidneys (type A1 in 30% and type A2 in 4.3%). type B calyxes, corresponding to minor calyxes draining directly into the renal pelvis, were present in 65.7% of the specimens (type B1 59.2%; type B2 6.5% of the cases). The number of minor calyxes in the collector system was 7.9 ± 2.27 with statistically significant differences in side (p = 0.0047). Conclusions: The morphometric characteristics of the kidneys in this study are slightly smaller than reported in humans. Similarly, the incidence of type A renal excretory system distribution is highest in humans and lowest in pigs. Due to its few morphological differences, the pig kidney is an excellent model for teaching- -learning processes, for research purposes, and for training of urologic applications.