Aglomerularism in Harpagifer bispinis a Subantarctic fish tolerant to sea water dilution

21. PÉREZ, A. CALVO, J. TRESGUERRES, M, LUQUET, C.

POLAR BIOLOGY

Springer

Lugar: Heidelberg; Año: 2003 vol. 26 p. 800 - 805

0722-4060

We investigated the renal morphology, histologyand ultrastructure of Harpagifer bispinis, as a firststep toward understanding the morpho-functional basisof its adaptation to potentially freezing brackish seawater.Fish were separated into two groups of ten individualseach, and acclimated to 2& and 38& salinity. Astudy of complete serial sections of the kidney revealedthat the nephrons were aglomerular. At the highlyconvoluted proximal segment two different regions wereevident, a feature that has not been previously reportedfor other aglomerular species. In electron photomicrographswe distinguished light and dark cells in theproximal tubule epithelium, with highly infolded basolateralmembranes and closely associated mitochondria.The dark cells also had a large number of mitochondriain the apical region. The intercellular spaces at the epitheliumof the proximal tubule were larger in fish acclimatedat 2&salinity, a modification that might facilitateurine secretion, thus contributing to the survival of anaglomerular fish in a hyposmotic medium.