Morphometric layers study of the gastrointestinal tract in New Zealand rabbits

Gastrointestinal diseases in rabbits represent a common disorder seen in veterinary practice. However, the normal histology of the rabbit gastrointestinal tract has not been well defined and there is little comparable data in literature. The aim of this study was to establish the specific different normal layers of thickness in the gastrointestinal tract and to provide accurate reference values useful in clinical and experimental studies. Whole sections of stomach (pars cardiac, fundus, pylorus), duodenum, jejunum, ileum, sacculus rotundus, caecum, apex ceci, ansa spiralis coli, colon descendens were obtained from five White New Zealand rabbits (8-14 months) with a mean weight of 5.24±1.04 Kg. These were processed and stained. For each section examined, we recorded 10 sample thickness measurements, measuring 4 tunics individually (serosa, muscularis, submucosa and mucosa) to obtain average representative morphometric values. The thickness of the intestinal wall was highest in the pylorus and sacculus rotundus, which was related to the maximum thickness of the muscularis and submucosa tunic, respectively. The mucosa is thicker in the small intestine and, proceeding from the duodenum to the ileum, there has been a progressive reduction of the total and mucosa thickness and an increase in muscular layer. Lastly, the serosa is thicker in the apex ceci. No notable correlation emerged with the sex of the subjects. This study gives values for the thickness of the layers in a rabbit's gastrointestinal tract, which should represent baseline information which could prove useful in the diagnosis of gastrointestinal pathology, specially in ultrasound and pathological anatomy.