Colonoid appearance in culture: Histological features.

At the end of the incubation period, colonoids were examined by light microscopy after staining with hematoxylin and eosin (a-g). Under all three conditions, the colonoids were found to be crypts of varying size with a single layer of epithelial cells surrounding a central lumen. Under control conditions (a), small crypts (with as few as 20 cells in cross section) were seen. In the presence of 1.5 mM calcium alone (b) or with Aquamin providing 1.5 mM calcium (e), larger crypts made up of columnar epithelial cells surrounding a large, often irregular-in-shape lumen were seen. With higher calcium concentrations, either from calcium (c and d) or Aquamin (f and g), crypts morphology was similar to calcium or Aquamin at 1.5 mM—i.e., with an increase in the lumen size and wall thickness. Goblet cells were apparent. Lumen size and wall thickness (h and i) measurements are shown in the accompanying bar graphs. Means and standard deviations are based on 74–123 individual crypts per condition. Asterisks (*) indicate statistical significance from control. Additional symbols indicate statistical significance as follows: ^ from calcium 1.5mM, O from calcium 2.1mM, with a significance at p<0.05 level. Bar = 100μm.