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Vliv modelové látky s anti-progestagenní aktivitou na vývoj gonád a štítné žlázy u žáby drápatky vodní (Xenopus laevis)
KARBUSOVÁ, Kateřina
The aim of this bachelor thesis was to assess the effect of the steroid hormone mifepristone, a model substance with anti-progestogenic activity, commonly used in medicine as an abortivum, on gonadal and thyroid development in a model amphibian species, the African clawed frog (Xenopus laevis). African clawed frogs were exposed to three concentrations of mifepristone 2, 22 and 215 ngl-1 from stage Nieuwkoop and Faber (NF) 47-48 until reaching stage NF 66. Mifepristone was dissolved in dimethyl sulfoxide (DMSO). The control group of frogs was kept in pure water with the addition of DMSO solvent at a final concentration of 0.001 %vol.. Images for gonad morphology were taken during dissection sampling at the end of the test (after reaching the juvenile stage). Furthermore, thyroid samples were processed for histological analysis. The thyroid gland on the histological slide was photographed with QuickPHOTO MICRO 3.2 software. Selected parameters were measured on the gonadal and thyroid images using image analysis in the QuickPHOTO MICRO 3.2 software and the effect of mifepristone on gonadal and thyroid development was evaluated. Exposure to mifepristone did not induce pathological changes in gonadal development, nor was intersexuality detected. No significant differences were found between the mifepristone-exposed groups and the control group for any of the parameters studied (gonad length and width, number of melanophores). Based on the observed parameters, we can conclude that mifepristone did not affect the gonadal development of exposed frogs. Histopathological examination of the thyroid gland also revealed no changes. Thyroid development, as assessed by the width of the thyroid follicular epithelium, was also not significantly affected by mifepristone exposure at any of the frog developmental stages studied (NF 58, NF 66). Although no effect of mifepristone on the parameters studied in this thesis was observed until the juvenile stage, it is possible that the effects could be seen in adulthood and further experiments are needed.
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