Rabbit lenses which were fixed, dehydrated and dried by a critical-point drying method were fractured through the cytoplasm of the differentiating lens fibers, exposing the cell nuclei. The fracture, under these conditions, caused a complete separation of the 2 membranes of the nuclear envelope from one another, exposing entire membrane surfaces (those which line the perinuclear space). These surfaces were not seen in their entirety in typical freeze-fracture or freeze-etch preparations, and were not described previously. The exposed membrane surfaces which line the perinuclear space had numerous convex structures of approximately 1000 .ANG. and some larger more irregularly shaped structures. These appeared to be fragments of the nuclear pore complexes. Differences in these structures between young fibers and those nearing completion of differentiation was suggested.