Computed Tomographic Anatomy and Topography of the Lower Respiratory System of the Mature Rat (Rattus norvegicus).

Abstract

Among various mammals, the laboratory rat (Rattus norvegicus) is widely used for experimental purposes and belongs to the order Rodentia, family Muridae, and genus Rattus. The lack of comprehensive studies on the topography and CT anatomy of thoracic structures in this species necessitates further investigation. This study aims to accurately describe the topography of the lungs, trachea, and heart in rats based on CT scan findings compared with anatomical observations. CT scan images were obtained from 10 adult male rats at 1 mm intervals using a Siemens Somatom Spirit CT Scanner, followed by anatomical studies through autopsy. Morphometric measurements were taken from the CT images, and the thorax, lungs, heart, and intrathoracic trachea, along with the spatial relationships of the organs, were meticulously examined during the anatomical studies. Detailed descriptions were compiled from both the CT scan images and autopsy findings. The tracheal bifurcation was consistently located between the fourth and fifth ribs in all samples. The right lung was larger and more voluminous than the left lung. The heart was oriented toward the left, and the right bronchus was shorter than the left. The results confirmed that the right lung was more voluminous than the left lung in R. norvegicus, as evidenced by precise measurements. It was also found to be longer than the left lung, although both lungs exhibited similar width and height. Notably, the use of CT scans enables anatomical examination of living and active body structures, which can be practically beneficial. In general, the lungs extend from the second rib to the last rib, with the right lung occupying slightly more space both anteriorly and dorsally. Regarding lobulation, the left lung consists of one lobe, while the right lung has four lobes. This study underscores the value of CT imaging in facilitating anatomical assessments in vivo, enhancing its practical applicability.