The central part of kidney wall is called medulla. It is light red in color. It consists of 8-18 pyramidal structures. It is called renal pyramid. The base of the pyramid faces the cortex and the apex faces the renal sinus. The top of the pyramid is called Papilla. Papilla with 10-25 pores. Apex of papilla opens into minor calyx. The minor calyxes open together into the major calyx. Also, the pillar-like part of the cortex between the two renal pyramids is called the Renal column. (iii) Pelvis: The large collecting space inside the kidney is called the pelvic floor. There are two types of branchial parts in the pelvis. There are 2-3 main branches. Major branches are called major calyxes. 8-14 minor calyxes arise from the major calyx.