Basal activity of the hypothalamo-pituitary-interrenal (HPI) axis changes over development in larval amphibians, but development of the responsiveness of this axis to an external stressor has not been studied. We compared developmental changes in whole-body corticosterone content of two anuran amphibian species, Rana pipiens (family Ranidae) and Xenopus laevis (family Pipidae). We also examined...

Birdsong is a prime example of acoustically sophisticated vocal behaviour, but its complexity has evolved mainly through sexual selection to attract mates and repel sexual rivals. In contrast, non-human primate calls often mediate complex social interactions, but are generally regarded as acoustically simple. Here, we examine arguably the most complex call in great ape vocal communication, the ...

1. Tail muscles of larval Rana temporaria and to a lesser extent Xenopus laevis, at prometamorphosis, were investigated by light and electron microscopy. In the case of Rana their degeneration is described at metamorphic climax. 2. The non-degenerate tail muscles of both genera are generally similar in their ultrastructure and likewise similar to those striated muscles of other adult vertebrate...

INTRODUCTION In a previous work on pronephric degeneration, larvae of Rana temporaria from practically the whole range of the metamorphic cycle were studied (Fox, 1962). Metamorphosis in anurans is dependent upon the presence of a functional thyroid gland (Kollros, 1951; Lynn & Wachowski, 1951; Etkin, 1964), and the same specimens have now been used to investigate thyroid growth and development...