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The evidence presently available supports a ' filtration '-reabsorption hypothesis for the mechanism underlying urine formation by the antennal gland of the crayfish. This evidence has been summarized most recently by Schmidt-Nielsen & Laws (1963) and by the writer (1963). In a previous paper (Riegel, 1963) the results of measurements of chloride(More)
Para-aminohippuric acid (PAH, 0.2 and 1 mmol l(-)(1)) had no effect on the basal fluid secretion rate (FSR) of isolated Malpighian tubules of Drosophila melanogaster Meig. and did not affect stimulation of the FSR induced by adenosine 3',5'-monophosphate (cAMP). Phenol Red (phenolsulphonphthalein, PSP; 0.5 and 1 mmol l(-)(1)) slowed the FSR and abolished(More)
In the course of investigations of the formation of urine by the antennal gland of the crayfish it was discovered that this process involved the secretion of formed bodies. The appearance and partial chemical analyses of the formed bodies of the crayfish are reported on elsewhere (Riegel, 1966). In the present report the lipid character of the walls of the(More)
Single glomerulus filtration rate in Eptatretus stouti averaged 20.3+/-2.13 (S.E.M.) nl min(-1). Single glomerulus glomerular filtration rate (GFR) could be correlated with arterial pressure when arterial pressure exceeded about 4 cm H2O. Glomerular filtration was affected by postglomerular resistance brought about by alteration of the volume of urinary(More)
Single renal corpuscles of hagfish were perfused with a Ringer solution containing Ficoll 70 to simulate the colloid osmotic pressure of hagfish plasma. Simultaneous measurements were made of single glomerulus filtration rate (SGFR), perfusion pressure and the pressure in a vessel of the renal vasculature. The results confirm that SGFR is independent of(More)
Ultrastructural studies on the Malpighian tubules of Glomeris marginata (Villers) reveal considerable morphological differences between the upper, fluid secreting, segment, and the lower segment which is at present of unknown function. Previous reports have shown that the upper tubule has a high permeability to compounds of high molecular weight. This may(More)