Development of the response of rabbit fetal tissues to thyroxine

The development of the response of rabbit fetal tissues to thyroxine was investigated by determining changes in α-glycerophosphate dehydrogenase activity of the liver mitochondria of pregnant rabbits and their fetuses during administration of thyroxine at different times of pregnancy. Until the 23rd day the activity of this enzyme increased only in the mitochondria of the maternal liver, whereas in the fetuses it remained at the control level. After the 24th day of pregnancy an increase in activity of this enzyme was observed in the fetuses also, where it can be explained by the appearance of the response of the rabbit fetal tissues to maternal thyroxine at this stage of development, and increasing until the end of pregnancy.