1. embryos are dissected from timed-pregnant mice from 11.5 d.p.c. to 13.5 d.p.c.

2. metanephroi and associated ureteric buds are microdissected and placed in holding medium (L15 medium supplemented with 1×MITO+ serum extender) (all media is supplemented with 100 U penicillin/ml and 0.1 mg streptomycin/ml)

3. metanephroi are allowed to sit in holding medium anywhere from 20 min to 2 hours

4. 0.2 ml of serum-free explant media (DMEM-F12 medium supplemented with 5×MITO+ with or without 10% fetal bovine serum) is added to each well of a six-well tissue culture plate containing Cyclopore (polyethylene terphthalate; Falcon Labware) inserts

5. metanephroi are transferred from the holding media onto the surface of the Cyclopore membranes (for transfer, the end of a 200 祃 pipette tip is removed with a sterile razor blade (to enlarge the hole), and metanephroi are taken up in 5 – 10 祃 of holding media)

6. metanephroi are grown on the tissue culture inserts in a 37℃ incubator under an atmosphere of 5% CO2

7. explant media is replaced every 48 hours

Metanephroi can be successfully grown for 7-10 days