Thyroid morphology and function and its role in thermoregulation in the newborn southern elephant seal (Mirounga leonina) at Macquarie Island.

摘要: The thyroid gland of the newborn southern elephant seal pup exhibits markedly increased secretory activity during first 24 hours after birth. Thyroid epithelial cell height is cuboidal to columnar for pups from birth 48 postpartum which it decreases by five days age. Ultrastructurally cells show pseudopodia protruding into lumen at zero, two and six After are rarely observed in follicles 20 old pups. number colloid droplets increases they distributed throughout cytoplasm. At days, few observed. Plasma T4 concentration three-fold birth, peak steadily declines. T3 eight-fold between postpartum. levels remain high until seven then decrease days. changes ultrastructure strongly suggestive secretion hormones postnatal life. This pattern similar that other mammals have been examined. active responsible elevated T3, thus playing a vital role maintaining body temperature when enters harsh environment sub-Antarctic.