The juxta medullary nephrons are one of the two types of nephrons found in the kidneys, specifically in mammals, including humans. These nephrons have distinctive characteristics and play crucial roles in the process of urine concentration, which is essential for water conservation and the regulation of blood pressure.

Option A: Juxta medullary nephrons are located in the columns of Bertin.

This option is incorrect. The juxta medullary nephrons are not located in the columns of Bertin. The columns of Bertin, or renal columns, are extensions of the renal cortex located between the renal pyramids. They consist primarily of lines of blood vessels and cortical material. The juxta medullary nephrons, however, have their renal corpuscles located at the deep cortex, close to the medulla, not within the columns of Bertin.

Option B: Renal corpuscle of juxta medullary nephron lies in the outer portion of the renal medulla.

This option is incorrect. In juxta medullary nephrons, the renal corpuscles are not located in the outer portion of the renal medulla but are located deep in the renal cortex, close to the medulla. The renal corpuscles include the glomerulus and Bowman's capsule, which are essential for the filtration of blood.

Option C: Loop of Henle of juxta medullary nephron runs deep into the medulla.

This option is correct. The defining characteristic of juxta medullary nephrons is the long loops of Henle that extend deep into the renal medulla. This structural feature is critical for establishing the conditions needed for the concentration of urine, as it allows for a significant reabsorption of water and solutes under the influence of various gradients.

Option D: Juxta medullary nephrons outnumber the cortical nephrons.

This option is incorrect. Juxta medullary nephrons are much less numerous than cortical nephrons. Cortical nephrons make up the majority of nephrons in the kidneys and are primarily involved in the filtering of blood and initial urine formation under different conditions.

In summary, the correct statement about juxta medullary nephrons from the provided options is Option C: Loop of Henle of juxta medullary nephron runs deep into the medulla.