The intestinal surface varies with nutritional factors, microbiota and diseases and objective measurements of villi length and crypt depth are used to estimate gut health. Crypt depth and villi height have been reported to vary depending on the intestinal segment sampled. However, these parameters also vary within a gut sample from a single intestinal site but few studies have addressed intra-sample variation.
We have investigated whether sampling procedure and measurement location within a sample can affect the result of the morphological evaluation of intestinal crypt length at a single intestinal site.
An intestinal segment of the ileum was sampled from twenty pigs aged 60 weeks. From each pig, one ileal sample was fixed as a closed circular gut-piece, and an adjacent gut sample was cut open and pinned out onto a piece of turnip before fixation. Images of tissue sections were captured at three different locations i.e. at the base, middle, and apex of intestinal circular plicas, in areas of the intestine with and without Peyer’s patches. Longitudinally sectioned crypts with epithelium visible from the muscularis mucosae to the crypt-villus-junction were measured.
There were differences in mean crypt depth both with sampling procedure and with measurement location. The crypts were significantly longer in the locations from plica containing Peyer’s patches compared with the locations from plica without Peyer’s patches. There were also differences in crypt depths between the three locations on intestinal plicas. There was less variation in crypt depths in the pinned samples compared with the closed gut samples.
This study showed that the procedure used to collect the sample and the location of the measured crypt within an intestinal sample can influence the obtained result.
These findings indicate that systematic sampling and measurement procedures that take into account intestinal anatomy and histology are needed when evaluating intestinal morphology.