Extracting Intact Kidney from Mouse: A Technique to Obtain Kidney Without Renal Capsule from Murine Models

In rodents, the kidney has a protective fibrous outer covering called the renal capsule and a layer of perinephric fat above it. To extract the murine kidney without the surrounding layers, begin by positioning a euthanized mouse in the supine position on a surgical bed.

Incise the abdominal skin and muscle layers. Continue to make longitudinal incisions until the abdominal cavity is exposed. Then, locate the intestines and lift them slightly. Cut underneath the intestines and remove them from the mouse's body to expose the kidneys.

Next, find the ureter and cut the underlying connective tissues so that the kidneys separate from the abdominal cavity. Excise both the kidneys individually. Place the extracted kidney into a dish containing an ice-cold buffer and observe it under a dissecting microscope.

Now, remove the perinephric fat from the kidney to visualize the renal pelvis, a funnel-like dilated part of the ureter. Snip off a portion of the renal pelvis from the base to remove the remnants of the ureter.

Finally, pierce the outer fibrous renal capsule superficially. Using the opening created, carefully peel the entire renal capsule from the kidney’s surface. This helps remove the adrenal gland - an endocrine gland attached to the renal capsule - and obtain an intact kidney.

Using internal tissue forceps and internal dissection scissors, pinch the intestines and lift them away from the abdominal wall. Simultaneously, cut the underside of the intestines free from the body at the proximal duodenum and distal colon to gain access to the retroperitoneal space containing the kidneys.

Gently pinch and lift the distal end of the ureter with tissue forceps. Using the dissection scissors, cut underneath the pinched ureter towards the kidney until it has become liberated from the surrounding connective tissue. Once the kidneys are exposed, extract them individually.

Fill a silicon elastomer-coated dish with ice-cold KRB solution. Transfer the kidney to the dissection dish and ensure that it is completely submerged. Use fine spring scissors and internal forceps to remove adipose tissue from the base of the kidney to expose the distal renal pelvis or RP and proximal ureter.

Remove the proximal ureter and a portion of the distal RP from the base using fine spring scissors and forceps. Pierce the outer renal capsule with fine-tip forceps, angling the tips away from the kidney body. Using forceps with each hand, pinch the loose ends of the capsule and peel them apart until the remaining renal capsule membrane is removed entirely.