[Placental permeability in rats and rabbits for thyroid hormones at different periods of pregnancy].

Upon the introduction of 14C-thyroxine in the rats on the 20th day of pregnancy, about 1/7 of the introduced radioactivity is found in the blood serum of the foetus; the labelled hormone is found in the foetus organs. The permeability of placenta at different times of pregnancy was also studied in rabbits. The placenta was shown to be permeable on the 23rd and 28th days of pregnancy, whereas earlier (16-17th days of development) negligible amounts of the labelled thyroxine introduced in the mother are found in the foetus organs.

[Lactation regulation and the content of thyroid hormones in the milk of parturients and components of infant food formulas].

The content of folliculostimulating (FSH), luteinizing (LH), thyrotropic (TTH) hormones and prolactin was studied in the blood serum of pregnant women and puerperants; also the thyroxin (T4), triiodthyronin (T3), thyroxin-binding globulin (TBG) levels, and the thyroxin-binding capacity of proteins and free T4 index were determined in the blood serum and milk of puerperants during the first week of lactation. The blood serum FSH, LH, TTH and prolactin concentrations underwent definite changes connected with physiological reconstruction of the organism at these periods. The milk T4 and T3 levels showed a sharp elevation by the 6th day of lactation, this correlating with the changes in the blood serum.

[Functional state of the pituitary-thyroid system of women during pregnancy].

Functional condition of the hypophysio-thyroid system was studied in physiological pregnancy by protein-bound iodine, T4, T3, thyrotropic hormone indices; the function proved to become more intense with the advance of pregnancy. A significant change of the T3 level during the early periods of pregnancy is possibly connected with the high hormone uptake at that period. A sharp elevation of the hormone-binding capacity of the blood serum proteins prevented the development of hyperthyroidism, this being confirmed by the results of the free thyroxin index determination.