Comparative morphologic and morphometric studies on the lower respiratory tract of adult Japanese quail (coturnix japonica) and pigeon (columbia livia)

Abstract

This study was concerned with the comparative evaluation of the morphologic and morphometric parameters of the lower respiratory tract of Japanese quail and that of pigeon. In the course of this work twenty birds (ten pigeons and ten Japanese quails) of both sexes were purchased from a poultry market in Sokoto metroplis, Sokoto, Nigeria and used. It was observed in this study that the lower respiratory tract extended from the caudal part of the oral cavity (around the larynx) down to the neck and to the thoracic region. The lower respiratory tract structures were the trachea (including the syrinx), the bronchus and the lungs. In the study, all the birds used were adults with mean body weight of 159.51±8.19g and 265.78±4.88g for the Japanese quail and pigeon respectively, this was considered extremely significant (P<0.05). The tracheal weight, length and diameter in the quail were 0.55±0.06g, 7.61±0.37cm and 0.47±0.04 cm respectively, while the pigeon had 0.79±0.11g, 8.13±1.10 cm and 0.51±0.06 cm as corresponding values respectively. The morphometry of other respiratory apparatuses were obtained and presented. In both subjects the lungs were small, compact and non-expandable and were both found to be bright red in color and impregnated within the rib cage with contacts on their dorsal surfaces by the thoracic vertebrae in such a way that they delineated vertebral impression on the lung surfaces which resulted in a division of the lungs into parts. The trachea was observed in both quail and pigeon to lie ventral to the esophagus along the length of the neck. There were complete tracheal rings comprising the windpipe and not C-shaped as in mammal, this probably is to provide better protection for the bird’s trachea which needs to move freely subcutaneously due to the long cervical region and the ability of the bird to twist the neck through a wide range of motion. Both right and left bronchus were observed to have originated from the trachea in both species entering the left and right lobes of the lungs respectively. These informations could be useful in comparative anatomy, pharmacological and toxicological investigations, and as well as aiding in the understanding of the biology of these two bird types used in this study.