Histo‐morphology of the thyroid gland during the larval development of Pleurodema borellii (Anura, Leptodactylidae)

Abstract

The thyroid gland is essential in anurans, since thyroid hormones (TH) are the main regulators of larval development. Its absence or inactivity interrupts development and precludes metamorphosis. Histological changes are important diagnostic criteria for evaluating thyroid gland activity. However, there is a large larval diversity where the development of the thyroid gland development has not been studied. Pleurodema borellii is an anuran from northwest of Argentina with typical omnivorous pond tadpoles that can be easily raised in captivity. This study explores the histo‐morphological changes of the thyroid gland architecture during larval development. Histological parameters indicate peak glandular activity in parallel with the intensity of the metamorphic transformations. These parameters regress towards the end of metamorphosis, indicating low TH release. P. borellii's thyroid gland does not appear to have relevant activity in post‐metamorphic juvenile stages. This study is a first step towards understanding endocrine regulation during the development of Pleurodema borellii, and a reference to future studies in this species involving thyroid‐dependent processes.