The functional state of the thyroid gland of the mother and fetus in the prenatal development of rabbits.

The functional state of the thyroid gland of the mother and fetus was studied in different periods of intrauterine development of rabbits, as well as in newborn rabbits according to the level of protein-bound iodine (PBI) in the blood plasma and thyroid gland tissue. Similar studies were conducted after a thyroidectomy of females on the 10th-12th day of pregnancy in order to demonstrate the possibility of mutual compensation of the hormonal function under pathological conditions. The level of PBI in the blood plasma of the mother clearly increases in the second half of pregnancy and decreases sharply after birth. The content of PBI in the fetal blood plasma increases continuously beginning with the 22nd day of intrauterine development. The level of PBI in the thyroid gland tissue both of the mother and the fetus increases sharply at the end of pregnancy. In fetuses of thyroidectomized females the amount of PBI in the blood plasma and thyroid gland tissue on the 22nd day of pregnancy considerably exceeded that in normal fetuses.