| dc.description.abstract | The kidneys of four freshwater teleost fish Oreochrom is
niloticus, Micropterus salmoides, Cyprinus carpio and Clarias
mossambicus and one marine teleost, Chanos chanos,
representing Perciformes (0. niloticus & M. salmoides)
Ostariophysi (C. carpio, & C. mossambicus ) and Salmoniformes
(C. chanos were studied for qualitative and quantitative
characteristics using materials fixed in silu by perfusion via
the bulbous arteriosus into the entire renal arterial system.
The kidneys of O. niloticus, M. salmoides and C. carpio we re
partially fused and those of C. mossambicus and C. chanos
were completely fused. Partial or complete venous portal
systems were prese0t 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
staining reactions and histological 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 around branches of the posterior cardinal
vein.
Rodlet cells have been described in the proximal tubule of
the blackbass.
Kidney volume 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% respectively; however, renal
haemopoietic tissue formed 31.62±4.38% in the kidneys of 3
species namely C. carpio, C. mossambicus and G. chanos). The
absolute volumes of the main components of the teleostean
kidney namely the uriniferous tissue (Vut) and the total
vascular space '(Vivs) 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 Vivs. = 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 | en |
