What does a mouse's lung look like? - briefly
A mouse lung is a tiny, reddish‑pink organ about 1 cm long, consisting of several thin, delicate lobes that create a spongy, highly vascularized tissue. Its surface is smooth and moist, with fine branching bronchi observable under magnification.
What does a mouse's lung look like? - in detail
The mouse lung is a compact organ occupying the thoracic cavity on either side of the heart. It measures approximately 10–12 mm in length and 6–8 mm in width in adult specimens, with a total mass of 0.15–0.25 g. The organ consists of five distinct lobes: the right lung contains four lobes (cranial, middle, caudal, and accessory), while the left lung is a single lobe. Each lobe is separated by thin pleural membranes and displays a smooth, glossy surface covered by visceral pleura.
The external architecture is dominated by a branching bronchial tree. The trachea divides into the main bronchi, which further subdivide into secondary and tertiary bronchi, forming a dichotomous pattern that terminates in numerous terminal bronchioles. These conduits are lined with pseudostratified ciliated columnar epithelium, interspersed with goblet cells that secrete mucus. Cartilage plates support larger airways, while smooth muscle encircles smaller bronchioles, regulating airflow.
Alveolar regions occupy the bulk of lung volume. Each alveolus is a thin-walled sac, typically 50–100 µm in diameter, surrounded by a dense capillary network. The alveolar wall comprises type I pneumocytes (flat cells facilitating gas exchange) and type II pneumocytes (cuboidal cells producing surfactant). Interalveolar septa contain elastic fibers and a modest amount of connective tissue, providing structural integrity and compliance. The total alveolar surface area in a mouse is roughly 0.5 m², sufficient for efficient oxygen uptake given the animal’s metabolic rate.
Vascular supply mirrors the airway hierarchy. The pulmonary artery follows the bronchial tree, branching into arterioles that terminate in capillary beds adjacent to alveoli. Venous drainage proceeds via pulmonary veins returning oxygen‑rich blood to the left atrium. A systemic bronchial circulation supplies the conducting airways, delivering oxygenated blood to the airway walls.
Microscopically, the lung parenchyma exhibits a uniform distribution of alveolar clusters, with minimal interlobular septa compared to larger mammals. The lack of a pronounced pleural fissure between lobes contributes to the organ’s overall rigidity. In histological sections stained with hematoxylin and eosin, the contrast between pink alveolar walls and the darkly stained nuclei of resident cells is readily apparent.
Key structural features include:
- Five lobes (four right, one left) with distinct pleural boundaries.
- Dichotomous bronchial branching ending in terminal bronchioles.
- Alveoli lined by type I and type II pneumocytes, surrounded by capillaries.
- Pulmonary artery and vein following the airway tree, providing efficient gas exchange.
- Thin visceral pleura covering the organ’s surface, facilitating smooth movement within the thorax.
These characteristics define the mouse lung’s morphology, distinguishing it from the larger, multi‑lobed human lung while preserving the essential components required for respiratory function.