Depigmentation and Prestaining of Zebrafish Kidney: A Technique to Prepare Adult Zebrafish Kidney for Staining

The adult zebrafish kidney is a translucent structure located adjacent to the dorsal body wall of the fish. The kidney exhibits the presence of superficial black spots corresponding to the scattered melanocytes - specialized cells that protect the kidney stem cells from harmful UV radiations.

To depigment and prepare the kidney for staining, begin by taking a euthanized adult zebrafish. Submerge the whole zebrafish in a suitable fixative solution and incubate for the desired duration. Incubation allows the fixative solution to penetrate the fish's body and lock the tissue components in place.

Next, place the zebrafish ventrally and remove its head. Make a long ventral incision starting beneath the head region and extending till the caudal fin. Remove the organs to expose the underlying kidney. Using forceps, detach the kidney from the dorsal wall and place it in a glass vial.

Treat the dissected kidney with an increasing concentration of sucrose solution. Sucrose solution creates an isotonic environment that prevents kidney shrinkage. Subsequently, incubate the kidney in a bleaching solution to remove melanocyte pigmentation. This helps in better visualization of the kidney during further staining procedures.

Finally, replace the bleaching solution with a blocking solution to block unwanted sites and prevent any nonspecific staining. The depigmented adult zebrafish kidney is now ready for subsequent staining steps.