Anatomy: The Sand Rat
The elaborate peripelvic columns in the sand rat maximize the possibility for exchange of water and solutes between the urine in the pelvis and the capillaries in the outer medulla. However, there is no evidence to suggest that the ability to concentrate the urine is enhanced in the mammals with the most elaborate peripelvic columns and complex pelvic extensions. There appears to be another explanation for the role of the fornices. This will be discussed later.

Sand rat papilla