Medullary gradient is mainly developed due to

The osmotic concentration in the interstitial fluid is primarily due to the presence of $.....$.

Henle's loop of nephron plays a significant role in maintaining a high osmolarity in

The shape of vasa recta is

If the Loop of Henle were absent from the mammalian nephron,which of the following is to be expected?

Select the correct option:
$(1)$ The counter-current mechanism is maintained by the Loop of Henle and the vasa recta.
$(2)$ The ascending limb of the Loop of Henle is impermeable to water.