Rins de Baleia Minke (Baleanoptera acutorostrata): arquitetura e estrutura

Abstract

Pesq. Vet. Bras. 32(8) Among marine mammals, whale is one of the most attention-arousing animals, especially concerning its urinary tract. This system follows the pattern of mammals with regard to its constitution, however, it differs in renal morphology and number of lobes, which, in turn, form complete reniculi, agglutinated in hundreds. This structure is supported by ϐi-brous connective tissue, but highly capable of maintaining electrolyte balance. Six pairs of kidneys of Minke whale (Balaenoptera acutorostrata), collected in 1982, in Cabedelo, Paraiba, Brazil, in the last ϐishing allowed, were dissected. These kidneys were preserved in 10% formaldehyde and they presented a very large histologic layer of collagen surrounding the medullary wall. The urinary collecting duct form papillary glasses, that reach a single collecting center which discharges in the ureter. It was found that the kidney of Minke whale has a lobe characteristic, with, on average, 700 reniculi; each reniculus has anatomical and functional characteristics of a unipyramidal kidney, with an inner layer (medulla), and an outer layer (cortex), and independent irrigation, with formation of individually arcuate arteries, as observed in unipyramidal terrestrial mammals. However, the set gathering all these reniculi constitutes, in the end, a multilobular and polipyramidal kidney, contrary to the morphology of most terrestrial mammals. It was not possible to distinguish the renicular cortex structures of the Minke whale in the level of light microscopy. Through scanning electron microscopy, it was possible to visualize a cortical layer located between two ϐibrous capsules. This joint, in turn, consists of connective tissue, which, along with a layer of collagen and elastic ϐibers, separates the cortex from the medulla; the kidney glomeruli were visualized, completely taken by the glomerular vessels and arranged into several layers. One notices that the glomerular cavity is almost a virtual space into which the glomerular ϐiltrate is drained, and it does not present a globular shape. Vascularization is increased in the medullary region.

Sonographic features of abdominal organs in healthy captive Neotropical otters (Lontra longicaudis)

“…The number of reniculi was not evaluated in the present study; however, in Eurasian otters ( Lutra lutra ), a total of 11 reniculi were reported (Stephens, 1957). In addition, macroscopic and histological evaluation of the Minke whale kidneys identified 700 reniculi, each of which had features of a unipyramidal kidney with a cortex and medulla (Sarmento et al., 2012). A previous study suggested that the reniculated kidneys of most marine mammals are probably related to a larger body size owing to the marine environment (Vardy & Bryden, 1981).…”