title: An ultrastructural and cytochemical study of the mesonephros of Rana esculenta during activity and hibernation.
abstract: The biological cycle of most amphibians undergoes seasonal variations. In this study, we investigated the mesonephros of Rana esculenta during active life and the natural hibernation period. The ultrastructural morphology of the different tracts constituting the nephron was analysed. Moreover, to evaluate the effect of seasonal temperature variations on the mesonephros function, the activity of some enzymes linked to membrane transport and playing regulatory roles in various metabolic pathways was investigated in different tracts of the frog nephron. During hibernation the glomerular filtration barrier appeared thicker than in the active life, lysosomes and paraplasmatic material, mostly glycogen, being accumulated in the proximal and distal tubule cells respectively. Cytoplasmic organelles, i.e., mitochondria, endoplasmic reticulum were observed in segregated areas. At the same time, changes in some enzyme activities were noted. The activity of some membrane-transport enzymes (5' nucleotidase and K+-p-nitrophenyl phosphatase) and of energetic metabolism (succinic dehydrogenase) was reduced. Nevertheless the alkaline phosphatase activity was not changed significantly, and this suggests that some metabolic activities were preserved in the hibernating samples. These results indicate morpho-functional adaptations of the kidney cells that preserve their role in osmoregulation and some metabolic processes, even during unfavourable seasons.
authors.affiliation: Dipartimento di Biologia Animale, Universita di Pavia, Italia.
authors.forename: C
authors.initials: C
authors.lastname: Fenoglio
authors.forename: R
authors.initials: R
authors.lastname: Vaccarone
authors.forename: P
authors.initials: P
authors.lastname: Chiari
authors.forename: M V
authors.initials: MV
authors.lastname: Gervaso
mesh_terms: D009597:4-Nitrophenylphosphatase / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D005260:Female; D006605:Hibernation / Q000502:physiology*; D006651:Histocytochemistry; D007685:Kidney Tubules, Collecting / Q000648:ultrastructure; D007687:Kidney Tubules, Proximal / Q000648:ultrastructure; D008297:Male; D008650:Mesonephros / Q000201:enzymology / Q000502:physiology* / Q000648:ultrastructure*; D008854:Microscopy, Electron; D010503:Periodic Acid-Schiff Reaction; D011893:Rana esculenta / Q000033:anatomy & histology* / Q000378:metabolism / Q000502:physiology*; D012621:Seasons; D013385:Succinate Dehydrogenase / Q000378:metabolism
chemical_list: D013385:Succinate Dehydrogenase; D000469:Alkaline Phosphatase; D009597:4-Nitrophenylphosphatase