THE ADRENAL GLAND OF XENOPUS LAEVIS (DAUDIN) (ANURA PIPIDAE): HISTOLOGICAL AND ULTRASTRUCTURAL OBSERVATIONS

SUMMARY The adrenal gland of Xenopus laevis (Daudin) (Anura Pipidae) shows anatomical, histological and cytological differences from that of other anurans. In Xenopus the gland is composed of small bodies, which extend along the whole length of the kidneys, near their medial edges. The vascular supply of the adrenals is greatly developed. The relationship of the chromaffin cells with the blood vessels is particularly intimate. The chromaffin cells are scarce and rarely innervated. The structure of the adrenal gland of Xenopus laevis is discussed, in comparison with the adrenal gland of other anurans and in relation to the phylogenesis of the Anura.