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Catecholamine- and cortisol- concentrations as well as metabolic parameters were determined on D18 until D21 in chicken embryos (Gallus gallus f. domestica).Eggs were incubated in one of three treatment groups. The control group was continuously incubated at 37.5°C. The eggs of the two other groups were also incubated at standard incubation temperature until D14. In the cold group incubation temperature was decreased to 35.0°C and in the warm group incubation temperature was increased to 38.5 °C. This means they were exposed to a changed incubation temperature for 4, 5, 6 and 7 days. Catecholamines were determined by HPLC and cortisol by an ELISA. Changed prenatal incubation temperature as easy adjustable environmental factor was chosen. Its influence on the avian embryo could be visible in changed hormone concentrations or metabolic parameters.The results show an age-dependant increase in catecholamine- as well as cortisolconcentrations in chicken embryos under standard incubation temperature during the investigated period of time.After decreasing incubation temperature the age dependant increase of the catecholamineconcentration can not be determined any more. A long term decrease of incubation temperature effects a lowered catecholamine concentration in plasma of chicken embryos compared to the control group.By contrast there is an age-dependant increase in cortisol in the cold group from D18 to D19 . On D19 cortisol concentration in this group is higher than in the control group. This can be assessed as embryonic response to a long term change of incubation temperature.After increasing incubation temperature the age dependant increase in catecholamine concentration remains from D19 to D20. Therefore increase in incubation temperature has less influence on age dependant changes in catecholamine- concentration than decrease in incubation temperature.Cortisol concentration increases likewise until D20. On this incubation day the concentration in the warm group is higher than in the control group. The portion of noradrenaline predominates over dopamine and adrenaline under each incubation condition and on every incubation day (NA>DA>A). As a rule changed incubation temperature results in an increase in dopamine portion and a decrease in adrenaline portion. The adrenaline portion increases age dependant from D18 to D20. It can be assumed that the proportionate changes of catecholamines have a physiological meaning in development of chicken embryos.On D20 the results of the present thesis show a new phenotype for that stage of development in embryos of the warm group concerning dopamine, adrenaline and cortisol as well as in embryos of the cold group regarding noradrenaline and adrenaline compared to the control group.The investigations of metabolic parameters came to the conclusion that increased incubation temperature has no influence. So in the control as well as in the warm group glucose concentration increases until hatch. In the same period of time 2,3-DPG decreases. No difference could be determined concerning hematocrit in the control- and warm group, too. The results of the present study contribute to a characterization of the adrenal-system shortly before hatch.