Thyroid hormones during development of a marsupial, the tammar wallaby, Macropus eugenii

The levels of thyroid hormones in the plasma and the activities of 5'-deiodinase activity in liver and kidney were determined in the tammar wallaby from early pouch life to adulthood.The findings suggest that the systems supporting synthesis and release of hormones from the thyroid gland are probably mature by about day 160 of pouch life in the tammar, while peripheral deiodinase activity, which is a major factor in the production of T 3 in the plasma, matures by about day 220.