This thesis examines the morphological and physiological changes that occur in the gills of the rainbow trout, Oncorhynchus mykiss, as a result of chloride cell proliferation. In the first component of this thesis (Chapter 2), the effects of chloride cell hyperplasia and hypertrophy on ion transport capability and the morphological diffusing capacity of the gill were evaluated. These experiments were performed to test the hypothesis that chloride cell proliferation benefits ionic regulation at the expense of efficient gas transfer. Concomitant with the surface morphology results, significant increases in Na$\sp+$ (J$\rm\sb{in}Na\sp+)$ and Cl$\sp-$ uptake (J$\rm\sb{in}Cl\sp-)$ were observed following treatment with the individual combined hormone regimens. Conversely, the gas morphological diffusion capacity, as indicated by the morphological parameters measured, of hormone treated fish was reduced, and was inversely correlated to chloride cell fractional surface area. Surface morphometric analysis showed that the hormone treatment increased the average chloride cell surface area by 2.7 x and chloride cell density by 2.2 x; the combined effect was a five-fold increase in chloride cell fractional area. While the P$\rm\sb aO\sb2$ values of hormone-treated and control fish were similar at P$\rm\sb wO\sb2>12.0$ kPa, the arterial O$\sb2$ tensions of treated fish were significantly lower than those of the control group for P$\rm\sb wO\sb2\leq12.0$ kPa. In comparison, to control fish at all environmental O$\sb2$ tensions, the hormone-treated fish exhibited elevated P$\rm\sb aCO\sb2$ values and a significant acidosis. The effects of chloride cell proliferation on blood gas parameters in hormone-treated fish were accompanied by significantly elevated ventilation amplitudes and lowered ventilation frequency. (Abstract shortened by UMI.)
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/6797 |
| Date | January 1994 |
| Creators | Bindon, Shawn. |
| Contributors | Fenwick, James C., |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 123 p. |
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