HISTOLOGICAL AND MORPHOMETRICAL STUDY OF THE OESOFAGUS IN ADULT DOMESTIC RABBIT (ORYCTOLAGUS CUNICULUS)

The rabbit oesophagus is a target organ used in neonatological surgery simulations, which cannot be reproduced by artificial simulators. The biological material used in this study was represented by five common breeds, 14 months old domestic rabbits. The rabbits come from an authorized breeder who slaughtered them for their consumption and on this occasion fragments from the three oesophageal segments were collected for histological investigations. The samples were fixed in 10% buffered formalin, embedded in paraffin, sectioned at a 5 mu m thickness and stained by Goldner's trichrome method. Histologically the wall of the oesophagus is composed as in all domestic animals of the mucosa, submucosa, muscularis externa and adventitia (in the cervical and thoracic segments) or serosa (in the abdominal segment). The oesophageal wall has a thickness that differs between certain limits, being the thickest in the abdominal portion. Structurally, the mucosa consists of the epithelium, lamina propria, and muscularis mucosae. The epithelium is stratified squamous with a tendency of keratinization, and the muscularis mucosae is composed of a discontinuous layer of smooth muscle fibers arranged longitudinally, with a thickness that increases progressively in an anteroposterior sense. No glands were identified in the mucosa and oesophageal submucosa of rabbits. The muscularis extema is composed of striated muscle fibers arranged in three layers, along the entire length of the organ. The inner muscular layer is arranged longitudinally, the middle circular layer, and the outer longitudinal layer. The thickness of the muscularis differs in the three segments, the thickest being in the abdominal segment, which seems to be a necessity related to the progression of the food bowl in the last part of the oesophagus. Adventitia and serosa are made up of loose connective tissue. The particular aspects reported in the components of the rabbit oesophagus are adaptive structures that appeared in response to the specifics of the diet.