I.Chester Jones

Influences of the adrenal cortex and the corpuscles of stannius on osmoregulation in the European eel (Anguilla anguilla L.) adapted to freshwater

Abstract In the freshwater eel, adrenalectomy resulted in a reduction of renal glomerular filtration rate, urine volume, and extrarenal uptake of Na. These together led to an increase in total water content, decline in plasma Na and Mg concentrations and hydration of muscle cells. Cortisol, at physiological doses, rectified both renal and extrarenal defects in the adrenalectomized eel. 11-Deoxycortisol was less effective, and aldosterone and DOC, in comparable doses, were without effect. After removal of corpuscles of Stannius, urinary Ca and Mg excretion declined while urine volume and total body water remained unaffected. Plasma Ca and K concentrations increased, but Na concentration decreased. There was a shift of water from the extracellular to the intracellular compartment in muscles. This shift of fluids might be related to the decline in systemic blood pressure. Intravenous infusion of corpuscular extracts raised blood pressure and increased renal excretion of Na and Ca. Corpuscular homotransplants also rectified Ca and Mg excretion. The significance of these findings and, in particular, the role of cortisol as a “mineralocorticoid” in teleost fish is discussed.

WATER AND ELECTROLYTE COMPOSITION OF THE BODY AND RENAL FUNCTION OF THE EEL (ANGUILLA ANGUILLA L.).

Abstract 1. 1. The water, sodium, potassium and chloride contents of serum and muscle of yellow and silver eels (Anguilla anguilla L.) in fresh water and sea water are given, together with urine output and glomerular filtration rates. ∗ . Ion concentrations m-moles/kg tissue H2O Type of eel Freshwater Seawater Na+ K+ Cl− Na+ K+ Cl− Serum ∗ 155 2·7 106 178 2·8 155 Parietal muscle 30·4 110·1 35·0 124·7 “Tongue” muscle 41·9 112·6 47·9 121·7 Urine ∗ 18·9 0·65 Nil 6·5 2·08 119·4 2. 2. The results are discussed in relationship to the general problem of the adaptation of vertebrates to water of differing tonicity.

The effect of mammalian calcitonin on the plasma levels of calcium and inorganic phosphate in the European eel (Anguilla anguilla L.)

Abstract Porcine calcitonin injected, in doses of 10 mU and 50 mU, into two groups of eels with sham operations, caused a rapid decline in total Ca concentration and a rise in phosphate levels in the plasma. Calcitonin was without effect in 4 out of 5 eels of a third group from which the corpuscles of Stannius had been removed.

Adaptation of the silver eel (Anguilla anguilla L.) to sea water and to artificial media together with observations on the role of the gut

Abstract 1. 1. Silver eels were transfered to a sucrose solution having the same osmotic pressure as sea water. Death occurred within 24 hr with considerable weight loss and wrinkling of the skin. Weight loss was not due to the absence of drinking. The addition of calcium and sodium in the ratios of 1 : 10 and 1 : 20 prolonged life for up to 6 days. 2. 2. Isolated gut sacs containing sea water were incubated in a Krebss saline medium at 25°C. After 2 hr there had been a passive influx of water from the incubation medium and from the gut wall tissue into the gut sac, representing an increase in volume of 18–46 per cent. 3. 3. The rate of passive water movements through preparations of posterior intestine was greater in seawater-adapted eels than in eels from fresh water. 4. 4. There was a passive efflux of sodium along a diffusion gradient, of 16–35 per cent in 2 hr, and sodium loss was greatest in the anterior intestine of freshwater eels.

Studies on Myxine glutinosa. I. The chemical composition of the tissues.

1. (1) Determinations were made of the concentrations of the major low molecular weight constituents in serum, muscle and liver of Myxine glutinosa L. (the Atlantic hagfish). 2. (2) The intracellular concentrations of the above substances have been calculated using the inulin space as a measure of the extra-cellular fluid compartment of the tissues. 3. (3) The concentrations of potassium, sodium and chloride in the intracellular water were 140–200, 110–150 and 100–120 mM/kg respectively. For potassium the ratio of the intracellular to extracellular concentration was 12 : 1. The corresponding ratio for sodium was 1 : 4·5. 4. (4) From the composition of the various tissues it is likely that serum and cells had the same osmotic pressure as sea water. Serum contained mainly inorganic ions and the intracellular fluid contained approximately equal quantities of inorganic and organic constituents. 5. (5) The major intracellular organic compounds were amino acids (20–70 mM/kg H2O), trimethylamine oxide (211–230 mM/kg H2O) and an unknown acidic substance about 200 mM/kg H2O).

Fine structure of the corpuscles of stannius of the trout, Salmo gairdneri: Structural changes in response to increased environmental salinity and calcium ions

Abstract These studies confirm that there are two cell types, C 1 and C 2 , in the corpuscles of Stannius (CS) of the trout, Salmo gairdneri , both of which have the appearance of protein-or peptide-secreting cells. C 1 cells have large secretory granules, up to 1.0 μm in diameter, while the C 2 cells have small granules up to 0.5 μm. In seawater (SW)-adapted trout the C 2 cell granules are significantly larger than those in freshwater (FW)-adapted trout. In fresh water the C 1 cells are relatively inactive and the C 2 cells are mainly sparsely granulated and actively secreting. The converse situation is found in seawater-adapted trout in which the C 1 cells are very active and the C 2 cells are relatively inactive and contain stored granules. During adaptation to SW from FW some C 1 cells develop extensive rough endoplasmic reticulum and Golgi but other C 1 cells degenerate and disintegrate apparently releasing the entire cell contents, including granules, into the capillary lumena. Protein may be released from these granules in capillaries by digestive enzymes from lysosome-like vesicles. In both adapted FW and SW corpuscles the active cells appear to release their granules by exocytosis. The appearance of C 1 cells of fish transferred from FW to calcium-enriched fresh water is similar to that of fish transferred to dilute SW, suggesting that these cells respond to high levels of external calcium, while the C 2 cells are active in media of low ionic and osmotic strength.

Histological and histochemical studies on the adrenal cortex and the corpuscles of Stannius of the European eel (Anguilla anguilla L.)

Abstract The adrenal cortex and the corpuscles of Stannius were examined in eels with methods that included buffered methylene blue to demonstrate RNA and those to show the presence of 3-beta-ol-steroid-dehydrogenase, as well as standard methods such as Masson-trichrome stain. The adrenocortical cells of eels kept in distilled water for more than 4 weeks had smaller nuclei, and the nucleoli were indistinct when compared with fresh water eels. The same could be seen in eels adapted to sea water for 2 weeks, but the cells looked normal after a longer adaptation period. Treatment with mammalian ACTH resulted in larger nuclei and very big nucleoli. After cortisol treatment the cells looked unstimulated, and after aldosterone treatment they appeared slightly stimulated. Infusion of 3% NaCl or H2O can also affect the histological appearance of the adrenocortical cells. The histology of the corpuscles of Stannius varied considerably. No steroid-dehydrogenase could be demonstrated. Significant histological changes occurred in the distilled water and sea water eels and after infusion of angiotensin. Then the corpuscles of Stannius were considered to be in an unstimulated condition, as judged by nuclear size and appearance of the nucleoli when compared with the freshwater eel.

The X zone of the mouse adrenal cortex of the Swiss albino strain.

The adrenal gland of the Swiss albino strain was investigated with particular reference to the X zone. The degeneration of the X zone in the male occurred concomitant with puberty. The unmated female possessed an X zone which gradually degenerated with age. First pregnancy gave a rapid disappearance of the zone. Gonadectomy preserved the X zone in both sexes, to decline with age. Hypophysectomy produced the classical sequelae, but injecting equine luteinizing hormone preserved the X zone. The X zone and its homologous/analogous representatives in various eutherian species differ from the pattern given in a common laboratory mouse. The difficulties are discussed.

Effects of adrenalectomy and cortisol injection on the in vitro movement of water by the intestine of the freshwater European eel (Anguilla anguilla L.)

Abstract The rate of water movement by the intestine of freshwater eels was measured using the technique of everted sacs from three segments: anterior intestine and the cephalad and caudad parts of the posterior intestine. Adrenalectomy produced a significant drop in the rate which was restored to normal values by injection of cortisol.

Drinking and urine production in the European eel (Anguilla anguilla L.).

Abstract The drinking rates of freshwater and seawater adapted eels at different temperatures were measured using polyvinyl pyrrolidine-131I. Concomitantly the urine production of freshwater eels was also measured. Freshwater eels acclimatized at 8°C had lower rates of drinking and urine production than those at 12° and higher figures were given by those at 23°. Unacclimatized eels at 23° gave the highest figures. Hypophysectomy was followed by reduced drinking rates and urine output and adrenalectomy gave the latter effect. Seawater cels at 12° had drinking rates about 6.5 times higher than those for freshwater eels at the same temperature. Hypophysectomy had no clear-cut effects.