[Experiments on the induction of embryopathies and changes in alpha-foetoprotein and serum albumin concentrations in the chick embryo].
Administration of 3 microg dexamethasone at day 8 of incubation into the allantoic cavity resulted in various embryopathies in embryos by the 15th day of incubation. Chicken alpha-foetoprotein (chAFP) and serum albumin concentrations, when examined at the 12th day of incubation, were below the corresponding controls (P<0.01), whereas total serum protein was only slightly lower, On day 15 chAFP concentrations were similar to those of the controls, serum albumin values were markedly reduced and total serum protein was significantly decreased. The results suggested a selective reduction of serum albumin synthesis in the 15-day-old chick embryo. Following administration of 2 IU insulin on the first day of incubation, into the yolk sac, one third of the embryos developed embryopathies. ChAFP, serum albumin and whole serum protein values were unchanged on either the 12th day or 15th day of incubation. Inoculation of 100 microg adrenaline into the allantoic cavity on the sixth day of incubation resulted in embryopathies in only a few instances. ChAFP total serum protein values were not affected. However, serum albumin concentrations were significantly lower on the 12th day, but not on the 15th. The responses to L-thyroxine were both time- and dose-dependent. Inoculation of 2 microg thyroxine on the second day of incubation resulted in few embryopathies. ChAFP levels were significantly lower on the 12th and 15th day of incubation. In contrast, serum albumin and total serum protein concentrations were normal at both times. Similar results were obtained when 2 microg of thyroxine were administered at the third day of incubation. Thus in order to inhibit selectively chAFP synthesis, administration of 2 microg thyroxine on day 2 or 3 of incubation is suggested. When 10 microg thyroxine were injected on day 8 of incubation, 80% of the embryos showed embryopathies on day 12 of incubation. ChAFP and serum albumin levels were markedly depressed. The concentration of total serum protein was significantly decreased on day 12 but less so, though still significantly, on day 15. These results demonstrate the possibility to influence selectively chAFP and serum albumin synthesis, thereby facilitating studies on chemically induced teratological, including pathophysiological, processes in the avian embryo.
Neumann
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U
Klinik fur Geflugel der Tierarztlichen Hochschule Hannover, Hannover 71, W. Germany.
Schäfer-Nolte
C
C