Which of the following structures has a hairpin shape?

In juxta-medullary nephrons,

Provide definitions/explanations for the following terms:
$(1)$ Column of Bertini
$(2)$ Excretory unit (nephron)

Identify the correct statements:
$I.$ The outer layer of the kidney is called a capsule.
$II.$ The kidney is divided into an outer cortex and an inner medulla.
$III.$ The medulla is divided into medullary pyramids.
$IV.$ The cortex extends in between the medullary pyramids,which is called the columns of Bertini.
Choose the correct option accordingly.

In the kidney of the rabbit,the $Loop$ of $Henle$ is the part of:

Name the following:
Cortical portions projecting between the medullary pyramids in the human kidney.