AB065. 229. On the growth and form of the mesentery
Kevin G. Byrnes1,2, Dara Walsh1,2, M. Fahad Ullah1, Omer Hashmi1, Daniel Westby1, Anna Garritt3, Rosa Mirapeix3, Wout Lamers4,5, Yi Wu7, S. Xiang Zhang7, Fabio Quondamatteo8, Peter Dockery8, Kieran W. McDermott2, J. Calvin Coffey1,2,8; Human Mesentery Project Consortium
Background: Systematic study of the mesentery has demonstrated that it is both continuous and spiral in nature from duodenum to rectum. Embryological planes are commonly exploited during abdominal surgery; however, the exact morphogenesis of the mesentery remains unknown. This study aimed to characterise the three-dimensional structure of the developing mesentery.
Methods: Embryological (n=12), foetal (n=4) and cadaveric (n=2) specimens were sectioned, stained and digitized. Regression analysis (SIFT; ImageJ2, v1.50e, NIH, USA) stacked sections in their true alignment. An internal panel of two reviewers verified manual tracings of regional anatomy and performed a double-blinded comparison of age-matched embryos. To test the reliability of manual tracing, five operators independently traced developing structures. Findings from three-dimensional outputs were further investigated with cadaveric dissection.
Results: Areas of mesoderm, endoderm and vasculature were reliably traced by operators [intra-class correlation coefficients 0.999 (95% CI, 0.998–0.999), 0.976 (95% CI, 0.938–0.994), and 0.995 (95% CI, 0.988–0.999) respectively]. Rendered volumes had a high degree of spatial overlap between operators [Sørensen-Dice similarity coefficient (mean ± SD) of mesoderm 0.9949±0.0085 (0.994–0.996), endoderm 0.9224±0.0067 (0.91–0.931), and vasculature 0.9379±0.00365 (0.933–0.944)]. Bland-Altman analysis demonstrated no systematic bias between operators. Three-dimensional visualisation of fore-, mid- and hindgut regions of the mesentery enabled identification of continuity between all regions in every specimen. Cadaveric dissection replicated three-dimensional observations.
Conclusions: The mesentery, continuous from mesogastric to mesorectal level, is the exclusive intermediate between viscera and the remainder of the body. This developmental model provides a structural framework for understanding and further investigating visceral and neurovascular development.
Keywords: Mesentery; embryology; development
doi: 10.21037/map.2018.AB065