Histological lung description of Caracara plancus (Miller, 1777) (Falconiformes, Falconidae) and Ardea alba (Linnaeus, 1758) (Pelecaniformes, Ardeidae)

Abstract

Histological studies in wild birds are still incipient, taking into account the great diversity of species and the difficulty to obtain material for analysis. Due to this scarcity, we aimed to describe the microscopic lung morphology of two terrestrial wild birds. To do this, we used a specimen of Ardea alba – Linnaeus, 1758 (great egret) – and a specimen of Caracara plancus – Miller, 1777 (southern caracara) –, which were taken to the Center for Rehabilitation of Wild Animals (CRAS) of Universidade Estacio de Sa (UNESA), in Vargem Pequena, Rio de Janeiro, Brazil, by members of civil society and government care and protection agencies; however, they did not survive their injuries and died naturally. The animals were dissected and their lungs were fixed in 10% formaldehyde aqueous solution, to apply routine histological technique, revealing a differentiated structure in the organ with a bronchial branching pattern that consists of mesobronchus, secondary bronchus, and parabronchus, as well as absence of classical lung alveoli, whose function is performed by air capillaries. Results point out the microscopic resemblance to poultry and confirm the complex architecture to enhance gas exchange.