The influence of thiourea on the development of the cultured quail embryo

Although thyroid hormones are known to promote embryonic development, it is still questionable whether the hormones of the thyroid gland exert a stimulatory effect on the early embryo. In attempting to elucidate the thyroid function in this period, we tried to block the synthesis of thyroid hormones by thiourea and followed the embryogenesis under these conditions. The experiments were performed with cultured quail embryos (Coturnix coturnix japonica), which seemed especially suitable for those studies. The results demonstrate that thiourea causes a decrease of the survival rate, DNA-synthesis and of the excretion of uric acid into the allantoic liquid. Furthermore, it exerts an inhibitory effect on weight gain and developmental stages. On the basis of these results it seems very likely, that thyroid hormones exert a stimulatory effect on the development of quail embryos earlier than assumed previously.