Integrating morphology and physiology of the key endocrine organ during tadpole development: The interrenal gland

Indirect development is widespread in anurans and is considered an ancestral condition. The metamorphosis of larvae into juveniles involves highly coordinated morphological, physiological, biochemical, and behavioral changes, promoted by the thyroid hormone and interrenal corticosteroids. Stress res...

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Bibliographic Details
Published in:Journal of anatomy 2022-12, Vol.241 (6), p.1357-1370
Main Authors: Regueira, Eleonora, O'Donohoe, M. E. Ailín, Pavón Novarin, Mariela, Michou Etcheverría, Gabriela C., Tropea, Carolina, Hermida, Gladys N.
Format: Article
Language:English
Subjects:
anuran
Blood vessels
Cell differentiation
Corticosteroids
Corticosterone
Cytoplasm
Developmental plasticity
Endocrinology
Environmental changes
Glands
Growth rate
histology
hormones
Juveniles
Metamorphosis
Morphology
Ontogeny
Phenotypic plasticity
Physiology
Steroids
Stress response
Thyroid
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Summary:Indirect development is widespread in anurans and is considered an ancestral condition. The metamorphosis of larvae into juveniles involves highly coordinated morphological, physiological, biochemical, and behavioral changes, promoted by the thyroid hormone and interrenal corticosteroids. Stress response to environmental changes is also mediated by corticosteroids, affecting the timing and rate of metamorphosis and leading to great developmental plasticity in tadpoles. Given the potential effect of interrenal gland ontogeny alterations on metamorphosis and the lack of studies addressing both the morphology and endocrinology of this gland in tadpoles, we present corticosterone (CORT) production and histological changes through the ontogeny of interrenal gland in the generalized pond‐type tadpole of Rhinella arenarum (Anura, Bufonidae). This species shows the highest concentration of whole‐body CORT by the early climax when drastic metamorphic changes begin. This is coincident with the morphological differentiation of steroidogenic cells and the formation of interrenal cords. By this stage, steroidogenic cells have a shrunken cytoplasm, with a significantly higher nucleus‐to‐cell diameter ratio. The lowest CORT concentration during premetamorphosis and late climax is associated with small undifferentiated cells with lipid inclusions surrounding large blood vessels between kidneys, and with cords of differentiated steroidogenic cells with a significantly lower nucleus‐to‐cell diameter ratio, respectively. Our study characterizes the morphological and physiological pattern of interrenal gland development, showing an association between certain histological and morphometric characteristics and CORT levels. Variations in this morpho‐physiological pattern should be considered when studying the phenotypic plasticity or variable growth rates of tadpoles. Interrenal gland hormones play a key role in regulating anuran metamorphosis. This study describes the association between interrenal development and corticosterone (CORT) production in a bufonid toad. The highest levels of CORT occur during the early climax, coincident with interrenal showing steroidogenic cells in cords with a high nucleus/cell diameter ratio. Changes in interrenal gland ontogeny should be considered when studying phenotypic plasticity or variable growth rates in tadpoles.
ISSN:0021-8782
1469-7580
DOI:10.1111/joa.13759