(Left) The hilus (Hi) shows in green a longitudinal section of the ureter (Ur) approaching the calyx (Ca) which is applied to the tip of the pyramid.

In this section the cortex (C) is deeply stained and reddish. The medulla (M) is paler and greenish. In the medulla two zones can be distinguished: the outer medulla (*) next to the cortex and the inner medulla (+), which occupies the tip of the pyramid.

Note that no sharp boundaries are evident between the zones of the kidney.

The clear spaces in the kidney parenchyma are vessels (V).

Stain: Masson’s Trichrome
Magnification: ×10