Does anyone know why heart cryos tend to separate? We've tried fresh frozen, NBF perfused, sucrose perfused and FBS perfused and the heart tissue has 'holes' in it. Laurie L. Pereira, RVT SDCADDL (County Veterinarian) 5555 Overland Avenue Suite 4103 San Diego, CA. 92123 Phone: 858-694-3384 Fax: 858-571-4268