Qualitative and Quantitative Structural Characteristics of Tile Teleostean Kidney.

Abstract

The kidneys of four freshwater teleost fish Oreochromis niloticus, Micropterus salmoides, Cyprinus carpio and Clarias mossambicus and one marine teleost, Chanos chanos, representing Perciformes (O. niloticus & M. salmoides) Ostariophysi (C. carpio, & C. mossambicus ) and Salmoniformes (C. chanos were studied for qualitative and quantitative characteristics using materials fixed in situ by perfusion via the bulbous arteriosus into the entire renal arterial system. The kidneys of O. niloticus, M. salmoides and C. carpio were partially fused and those of C. mossambicus and C. chanos were completely fused. Partial or complete venous portal systems were present in all the species except O. niloticus. The renal lobule was centered around the intralobular artery and duct and delimited by efferent veins. The nephron of the fishes consisted of a renal corpuscle, the neck, proximal I, proximal II and distal segments and the collecting tubule-collecting duct system. These parts of the nephric tubule were distinguished on the basis of their stai ning reactio ns and histo log ical and ultrastructural characteristics. Intrarenal heamopoietic tissue was absent in the Perciformes teleosts but was abundant in the Ostariophysi and Salmoniformes. Interrenal tissue in the head kidney was arranged in cords arou nd branches of the posterior cardinal vein.Rodlet cells have been described in the proximal tubule of the blackbass. Kidney voiume per gram body weight ranged from 2.2-6.13 m m 3/g and was well correlated with body weight, the correlation coefficient (r) was 0.96. The allometric equation relating kidney volume (Vk) to body weight (W) was Vk == 3.236WO.977. The mean (±S.D.) values for the volume proportions of uriniferous tissue, total vascular space (all blood vessels and capillaries), ureter and its ducts and connective tissue were 52.56±14.93%, 29.59±2.20%,4.04±2.44% and 2.43±0.83°/0 respectively; however, renal haemopoietic tissue formed 31.62±4.38% in the kidneys of 3 species namely C. carpio, C. mossambicus and C. chanos). The absolute volumes of the main components of the teleostean kidney namely the uriniferous tissue (Vut) and the total vascular space (Vtvs) were strongly correlated with body weight and the allometric equations and correlation coefficients relating these parameters were: Vut = 1.102W1.077, r = 0.97 and Vtvs = 1.197W1.025, r = 0.96 respectively. The fish were divided into three categories each with two groups with contrasting characteristics; (1) percoid and ostariophysian, (2) fish with and without intrarenal haemopoietic tissue and (3) freshwater and marine fish. In each category Student's t-test was used to assess the differences between kidney weight per gram body weight and those between the respective volume proportions of renal corpuscles, uriniferous tissue, total vascular space and renal tubules. The differences between the values of all parameters, except the kidney volume per gram body weight and the volume proportions of renal tubules in freshwater and marine fish, in the two groups of each category were significant (P < 0.05). These results show that the quantitative characteristics of the teleost kidney are influenced by the order, habitat and distribution of intrarenal haemopoietic tissue.