PHOTO 5 - Rat kidney
Rat kidney.
In vivo staining with Alcian Blue.
Cross section.
Note that the transition between OS and IS is well delimited (by the transition from pars recta to thin descending limbs), while the limit between cortex and OS is more irregular.
L. Bankir, NK. Hollenberg.
Renal Physiology (Basel) 6:151-155, 1983