In Kidney which of the following is true?

Ans. is'd'i.e., Osmolarity of medullary interstitium is more than plasma(Ref: Guyton 12/e p. 334)The renal medulla shows an increasing osmotic pressure with increasing depth.Staing, with an osmolarity of 300 mOsm/L in the coex, the osmolarity reaches a level of 1200-1400 mosm/L at the pelvic tip of the medulla, i.e., The inner pa of medulla has highest osmotic gradient.That means that the renal medullary interstitium has accumulated solute in greater excess of water.