Differences in the thyroxine, triiodothyronine and reverse triiodothyronine contents of fetal pig tissues relative to gestational age.
The concentrations of thyroxine (T4), 3,5,3'-triiodothyronine (T3) and 3,3',5'-triiodothyronine (reverse T3) were measured in the liver, kidney and skeletal muscles of pig fetuses from day 32 to 113 of age. The iodothyronines were found to be present already between days 32 and 39, that is before the onset of fetal thyroid function. In the liver, kidneys and skeletal muscles T4 reached maximal concentrations at midgestation (days 56 and 93). The T3 level increased with gestational age in all tissues examined but, as opposed to T4, its maximal value was reached shortly before birth. The rT3 level was the highest between days 85 and 100 in the liver and kidney; however, in the skeletal muscles it did not change with gestation. The presented profiles of change of T4 and rT3 in the examined tissues did not correspond to the blood hormone pattern already observed in pig, whereas changes in tissue T3 concentrations were similar to those in the serum.
Krysin
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Centre for Agrotechnology and Veterinary Sciences, Polish Academy of Sciences, Poznań, Poland.
D000818:Animals; D005260:Female; D005333:Fetus / Q000737:chemistry* / Q000378:metabolism; D007668:Kidney / Q000737:chemistry / Q000196:embryology / Q000378:metabolism; D008099:Liver / Q000737:chemistry / Q000196:embryology / Q000378:metabolism; D018482:Muscle, Skeletal / Q000737:chemistry / Q000196:embryology / Q000378:metabolism; D011247:Pregnancy; D011863:Radioimmunoassay; D013552:Swine / Q000196:embryology* / Q000378:metabolism; D013974:Thyroxine / Q000032:analysis* / Q000378:metabolism; D014284:Triiodothyronine / Q000032:analysis* / Q000378:metabolism; D014285:Triiodothyronine, Reverse / Q000032:analysis* / Q000378:metabolism
D014284:Triiodothyronine; D014285:Triiodothyronine, Reverse; D013974:Thyroxine