Figure 1.

Net calcium absorption and secretion by intestinal section during suckling and after weaning. A pictorial representation of current evidence. Absorption is represented by a downward arrow indicating net movement of calcium from lumen to serosa. When both transcellular and paracellular pathways are present in a segment, a larger arrow indicates the predominant pathway. Note that the transcellular pathway in the duodenum pre-weaning occurs after 1–2 weeks of age in rodents. The dashed line indicates that evidence supporting the pathway is limited. Evidence for calcium absorption in the cecum is from animal models only. Weaning is at 21 days in rodents. ND: no data. (A color version of this figure is available in the online journal.)