Outer nuclear membrane Nuclear lamina Nuclear envelope Inner nuclear Nucleolus membrane Chromatin Perinuclear space Ribosomes 1 um Figure 16-26 The Structural Organization of the Nucleus and Nuclear pores Nuclear Envelope.(a)An electron micrograph of the nucleus from a mouse liver cell,with prominent structural features labeled(IEM).The CYTOSOL nuclear envelope is a double membrane perforated by nuclear pores(NP). Internal structures include the nucleolus(nu),euchromatin (eu),and heterochromatin(he).(b)A drawing of a typical nucleus.Structural Rough ER features included here but not visible in the micrograph include the nuclear lamina,ribosomes on the outer nuclear membrane,and the (b) continuity between the outer nuclear membrane and the rough ER. 主讲：汤 华 5