Experimental studies on amphibian oocyte nuclei I. Investigation of the structure of the nuclear membrane by means of the electron microscope

Abstract The membrane surrounding the nucleus of the oocytes of two species of amphibian is shown to consist of two structures, an outer porous layer and an inner layer which is apparently continuous. The porous layer is about twice as thick as the inner layer, the dried membrane as a whole having a thickness of approximately 500 Å. The pores are of regular size and arrangement in the outer layer; pore diameter is approximately 400 Å, the separation distance between pore centres 1000 Å. Both layers consist of relatively insoluble protein materials, the porous layer also containing some lipoid.