The present study was undertaken to determine whether or not maternally derived thyroid hormone is transported by the placenta to the fetal circulation and thence to fetal tissues throughout normal fetal life in the Macaca mulatta (macaque) monkey.
Trapping and organification of iodide(s) by fetal thyroid tissue in the human and monkey is established early in the second trimester of pregnancy and then proceeds at a rapid pace to term.1-3 Such very active fetal thyroid gland growth and hormonogenesis is obviously necessary to at least provide a term fetus with a proportioned tissue mass containing hormone in quantities sufficient to initiate and thereafter, with continuing hormonogenesis, maintain thyroid homeostasis during extra-uterine life. It is not known whether fetal thyroid glands must also supply all or part of the thyroid hormone required on a day-to-day basis by the fetus.
The rapid rate of thyroid gland growth and associated highly active
PICKERING DE. Maternal Thyroid Hormone in the Developing Fetus: Observations on Monkeys (Macaca Mulatta). Am J Dis Child. 1964;107(6):567–573. doi:10.1001/archpedi.1964.02080060569003
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