What are bundles of collecting ducts that transport urine made by nephrons to the calyces of the kidney for excretion?
cuticle
cartoid
esophagus
papillae
Internal Anatomy A frontal section through the kidney reveals an outer region called the renal cortex and an inner region called the medulla (Figure 25.8). The renal columns are connective tissue extensions that radiate downward from the cortex through the medulla to separate the most characteristic features of the medulla, the renal pyramids and renal papillae. The papillae are bundles of collecting ducts that transport urine made by nephrons to the calyces of the kidney for excretion. The renal columns also serve to divide the kidney into 6–8 lobes and provide a supportive framework for vessels that enter and exit the cortex. The pyramids and renal columns taken together constitute the kidney lobes.