Perinuclear space

Somlyo Regarding the nuclear envelope and Ca2+, there is an old picture in a book showing strontium in the nuclear envelope within the perinuclear space (Somlyo Somlyo 1975). The trouble is, when we load with calcium oxalate, we can get an egg shell of calcium oxalate around the nucleus, but when we do electron probe analysis under normal physiological conditions, there doesn t seem to be detectable Ca2+ in the nuclear space. However, this is probably because there is no calsequestrin or other Ca2+ binding protein present. 

Although intermediate filaments are not universally associated with the cytoskeleton, neutrophils possess intermediate filaments of the vimentin type. Vimentin is a rod-shaped molecule of relative molecular mass 57 kDa that readily polymerises under physiological conditions to produce stable filaments 10-12 nm in diameter. Intermediate filaments are more robust than microfilaments and microtubules, and in neutrophils they form an open network of single filaments in the perinuclear space. 

Nuclear Envelope The membrane system of the cell nucleus that surrounds the nucleoplasm. It consists of two concentric membranes separated by the perinuclear space. The structures of the envelope where it opens to the cytoplasm are called the nuclear pores (nudear pore). [NIH]... 

The nucleus is separated from the cytoplasm by the nuclear envelope, which consists of the outer and inner nuclear membranes. Each of the two nuclear membranes has two layers, and the membranes are separated from each other by the perinuclear space. The outer nuclear membrane is continuous with the rough endoplasmic reticulum and is covered with ribosomes. The inner side of the membrane is covered with a protein layer (the nuclear lamina), in which the nuclear structures are anchored. 

Each cell nucleus contains one or more dense nucleoli, regions that are rich in RNA and may contain 10-20% of the total RNA of cells. Nucleoli are sites of synthesis and of temporary storage of ribosomal RNA, which is needed for assembly of ribosomes. The nuclear envelope is a pair of membranes, usually a few tens of nanometers apart, that surround the nucleus. The two membranes of the pair separate off a thin perinuclear space (Fig. 1-7). The membranes contain "pores" -130 ran in diameter with a complex structure (see Fig. 27-8).38/39 There is a central channel -42 ran in diameter, which provides a route for controlled passage of RNA and other large molecules from the nucleus into the cytoplasm and also from the cytoplasm to the nucleus. Smaller -10 nm channels allow passive diffusion of ions and small molecules. 

The outer nuclear envelope (ONE) is surrounded by other intermediate fibres, and is essentially just the RER surrounding the nucleus, and continuous with it. The space between the INE and ONE is termed the perinuclear space, and is continuous with the RER cisternae. 

Fig. 48. Electron microscopic photograph of a cell nucleus with a connection to the endoplasmic reticulum at X . n nucleus ne = nuclear membrane with perinuclear space m = membrane of the endoplasmic reticulum (= er). Enlargement 27,000-fold. (Photograph by K. R. Porster)...

The nuclear content of a normal cell (without giant chromosomes) does not reveal any details with the electron microscope it consists merely of granular or fibrillar structures. Deoxyribonucleic acid usually cannot be distinguished. The nuclear membrane consists of two lamellae which enclose the so-called perinuclear space. The latter is in contact with the cisternae of the ergastoplasm (see below). In the nuclear membranes pores can be seen that are usually closed by a very fragile diaphragm. 

This cellular structure, closely related to the nucleus, consists of two components a membrane and small granula. With the electron microscope a three-dimensional network of tubules and globules with a diameter of 100-150 m/i can be distinguished. The interior (cisternae of the ergastoplasm) of these structures is encased in a membrane, on the outside of which are attached small granula with a diameter of 15 m/j. The granula are the ribosomes, a subdivision of the microsomes (cf. Fig. 47 and 48). The interior appears to be connected with the perinuclear space, and sometimes also with the extracellular space (through pores in the cell surface). The endoplasmic reticulum is very well developed in tissues with active protein synthesis, e.g. in exocrine cells of the pancreas. 

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