[State of the pituitary--thyroid gland system in pregnant rabbits, fetuses and newborn rabbits]

The paper deals with the study of the functional condition of the hypophysis-thyroid system in pregnant rabbits and their fetuses during last trimester of gestation. The 131I uptake and the hormonal synthesis proved to be increased in the maternal and fetal thyroid glands during the 12rd--27th days of pregnancy; this was confirmed by the changes in the histostructure of the gland and was apparently connected with the increased thyroxin requirement in the maternal-fetal system at this period. These changes were preceded by the enhancement of the thyrotropic function of the hypophysis. No such correlation was present in the fetus. These data served as the evidence that the functional activity of the maternal hypophysis-at the functional activity of the maternal hypophysis-thyroid system rapidly changed depending on the requirement of the pregnant organism in thyroid hormone.