Heart muscle and renal cortex prefer acetoacetate over glucose. Renal gluconeogenesis takes place in the renal cortex. Erythropoietin is produced in the renal cortex. They are located at the border of the renal cortex and renal medulla. It is located at the border of the renal cortex and renal medulla. This hypotonic filtrate is passed to the distal convoluted tubule in the renal cortex. The collecting duct system begins in the renal cortex and extends deep into the medulla. The renal cortex is the part of the kidney where ultrafiltration occurs.