Minor calices

The minor calices are small, funnel-shaped structures located in the renal sinus of the kidney. Each minor calyx surrounds the apex (renal papilla) of a renal pyramid and serves to collect urine produced by that individual pyramid. The urine collected in multiple minor calices then drains into larger structures called major calices, which subsequently empty into the renal pelvis and then the ureter.

Minor calices are an essential part of the excretory pathway, and while they are prominent in species like dogs and cats, their number and structure may vary between species. In some animals (e.g., ox and pig), the caliceal system is more complex and clearly segmented, while in others (e.g., horse), the renal pelvis is more dominant and calices may be reduced or absent.