Structure and histology of the wattle in the White bellbird (Procnias alba)



Structure and histology of the wattle in the male White bellbird (Procnias alba) are described. The proximal two-thirds of the wattle contains only very sparse, frail connective tissue and is isolated both from the respiratory tract and from pneumatic spaces in the skull. The wattle is richly vascularized, with an extensive network of veins, which completely fill the lumen in the distal third. The larger veins possess longitudinal as well as circular muscle. Longitudinal muscle bundles (some associated with feather follicles) are scattered in the loose connective tissue of the periphery. The wattle is compared in structure with the superficially similar frontal process of the turkey (Meleagris gallopavo). The mechanism of extension and retraction is discussed.