The cell nucleus is the organelle of the eukaryotes responsible for maintaining the integrity of DNA and for controlling cellular activities such as metabolism, growth, and reproduction by regulating gene expression. It is a double-membraned organelle and this double membrane is referred to as nuclear envelope (also called nuclear membrane, plasmalemma, sor karyotheca). The nuclear envelope surrounds most of the eukaryotic cell’s genetic material as opposed to the genetic material of the prokaryotes that is not membrane-bound. The space in between the two membrane layers is called perinuclear space.
The perinucluear space refers to the gap between the inner and outer membranes of the nuclear envelope. Most cells have about 20-40nm wide perinuclear space. Since the endoplasmic reticulum is contiguous to the outer membrane of the nuclear envelope the endoplasmic reticulum lumen is therefore contiguous to perinuclear space as well.
The nuclear envelope is a lipid bilayer. Intervening the perinuclear space are the nuclear pore complexes that span the nuclear envelope. The nuclear pore complex is the part of the nuclear envelope that regulates the entry and exit of biomolecules across the lipid bilayer.
Common biological reactions
During cell division, the nuclear envelope undergoes major changes in animal and plant cells. The nuclear envelope disintegrates to allow the spindle fibers to access the chromosomes in the nucleus. An exception to this is the yeast cells whereby the nuclear envelope stays intact during cell division. In animal and plant cells, the nuclear envelope breaks down into pieces during prometaphase of mitosis. Then, during telophase, the nuclear membrane reforms. The reformation process remains unclear how it proceeds. It is postulated to occur via vesicle fusion or probably by reshaping of the endoplasmic reticulum, enclosing the nuclear region with a new nuclear envelope.
- peri– (surrounding) + nuclear (nucleus) + space
- perinuclear cisterna
- nuclear envelope lumen
- Cisterna caryothecae
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