Influence of autonomous regulation type on the structure of the thoracic esophageal wall in rabbits

The study investigates the relationship between the structure of the thoracic esophageal wall in rabbits (Oryctolagus cuniculus) and the autonomous regulation type. Male rabbits of the Blanc de Termonde breed were divided into three groups based on electrocardiographic and variational-pulsometric examinations: sympathotonic rabbits (ST), parasympathotonic rabbits (PST), and normotonic rabbits (NT). After euthanasia, esophageal wall samples were embedded in paraffin blocks, from which histological preparations were made. Using morphometric analysis, the thickness of individual layers and their structural components was determined, along with their interrelations. Within each group, most of the studied parameters exhibited low and moderate variability. Exceptions included the serous membrane across all types of autonomous regulation and the outer longitudinal layer of the muscular membrane in PST rabbits. Overall, the muscular elements of the esophageal wall (the muscularis mucosae and layers of the muscular membrane) were the most sensitive to the typological features of autonomous tonus, since they demonstrated significant differences between groups. However, no single type of autonomous regulation exhibited a consistent superiority in all examined parameters. Sympathotonia was associated with greater thickness of the epithelium, lamina propria of the mucosa, and submucosa. Normotonia resulted in the thickest mucosa, muscularis mucosae, and the serous membrane. Parasympathotonia led to the maximum thickness in most parameters, including the entire esophageal wall, keratinized epithelial layer, the entire muscular membrane, and all three of its layers. Overall, the total esophageal wall thickness was greatest in PST rabbits (1218.23 ± 9.03 µm). It was 108.06 µm thinner (P < 0.05) in ST rabbits and 164.29 µm thinner (P < 0.05) in NT rabbits. Correlation analysis revealed associations between various parameters within each group, with most correlations linked to the layers of the muscular membrane. The morphological characteristics studied reflect the adaptive properties of the esophageal wall in response to the features of autonomous tonus in rabbits.