Histology and Scanning Electron Microscopy of the Lower Respiratory Tract in the Adult Red Fox (Vulpes vulpes)

Abstract

SUMMARY:The study was conducted on a total of three adult healthy freshly killed red foxes of both sexes weighing about 4-6 kg collected from Abou Rawwash, Giza, Egypt. The wall of trachea and bronchi formed of mucosa, submucosa and adventitia. The mucosa formed of pseudostratified columnar epithelium and lamina propria. The respiratory epithelium composed of tall columnar ciliated, goblet cells, basal cells, and neuroendocrine cells. Goblet cells account for about 20 to 30% of cells in the more proximal. Basal cells are relatively small triangular cells whose bases are attached to the basement membrane. The primary bronchiole is lined by simple columnar nonciliated to cuboidal epithelium containing some bronchiolar exocrine cells and some goblet cells. Neuroendocrine cells constitute about 4 to 5% of bronchial epithelial cells, attached at their bases to the basement membrane and have tapering apices. The lamina propria consists principally of a network of capillaries, a meshwork of connective tissue fibers continuous with the basement membrane. The submucosa formed of connective tissue elements and blood vessels and devoid of Tracheobronchial glands in red fox. The adventitia contain tracheal cartilage and muscle in trachea and bronchial cartilages and muscles in bronchi. Tracheal muscle is transverse bundles attached to the outer perichondrium. In the bronchi, muscle is organized in transverse bundles close to the epithelium adjacent to the lamina propria and longitudinal bundles close to the cartilages. Alveoli are demarcated by septa composed of a continuous layer of epithelial cells overlying a thin interstitium. The epithelial cells consist principally of type I and type II pneumocytes. SEM revealed that, the mucosal surface of both trachea and bronchi was completely covered by cilia. There were few glandular openings or goblet cell.

Macroscopic and microscopic morphology of the trachea and lungs of giant anteater (Myrmecophaga tridactyla)

“…Although this segment is short, it is also covered by the mandibular salivary gland. In the present study, tracheal mucosa was coated by the respiratory epithelium and had serous glands, similar to the description made for domestic (Banks 1993) and wild species (Moussa & Hassan 2015, Rocha et al 2017, Mario et al 2018. The tracheal muscle was inserted in the tracheal cartilage's internal face, similar to horses, pigs, and ruminants, but different from carnivores and humans, whose muscle fixation occurs on the external surface of the tracheal cartilages (Bacha & Bacha 2012, König & Liebich 2016.…”

“…Pulmonary structures composing the gas exchange apparatus are similar to those described for domestic (Banks 1993) and wild animals (Smodlaka et al 2006, Oliveira et al 2011, Cope et al 2012, Moussa & Hassan 2015, Rocha et al 2017. However, different from what was reported for such animals, there were no alveolar macrophages in giant anteaters.…”

“…All these features were also observed in pulmonary tissue collected from giant anteaters in the present research. The assessed bronchioles presented simpler morphology; cartilage and glands, similar to domestic animals (Bacha & Bacha 2012), human beings (Junqueira & Carneiro 2013), and to animals such as quaint (Monodelphis domestica) (Cope et al 2012) and red fox (Moussa & Hassan 2015), the absence of these structures is the primary way of differentiating bronchioles from the bronchi.…”

Histological description of Cerdocyon thous (Linnaeus, 1766) respiratory system

“…This suggests the occurrence of regionalization of goblets cells, described in carnivores by Samuelson (2007), indicating the maintenance of a "trails" distribution in crab-eating fox. This regionalization seems not to be present in the red fox (Vulpes vulpes) trachea (Moussa & Hassan 2015). Another specific carnivore characteristic present in C. thous trachea is the smooth muscle belt around hyaline cartilage piece, rather than internally located smooth muscle (tracheal muscle) present in humans.…”

Morfologia da traqueia e lobação pulmonar de Leopardus pardalis (jaguatirica)

“…Nos aspectos microscópicos a traqueia diferiu em relação ao seu epitélio, que se mostrou não ciliado, as demais estruturas constituintes dos órgãos eram similares a Bradypus variegatus (Faro et al 2015), N. nasua , Cricetomys gambianus (Ibe et al 2011) e Vulpes vulpes (Moussa & Hassan 2015). Em relação às constrições nos arcos de cartilagens não foi encontrada na literatura nenhuma informação referente a esta característica.…”