English: FRIL is a technique where a specimen in fractured to reveal the internal structures of a specimen, a replica made, and material on the replica labelled with 5nm immuno-gold coupled anti-connexin 46 (Cxn46) antibodies . In this case untreated snap frozen sheep lens is broken to reveal the interior of the cells membranes. The top of the micrograph is mainly smoother membrane with smaller rough patches usually correlating to intramembrane proteins such as aquaporins. The lower part is much rougher and forms part of a gap junction plaque containing the Cxn46 protein. When viewed as a large image the lower part of the picture can be seen to be peppered with gold beads averaging 5nm in size that had been coated with the anti-CXN 46 anti-body.