cell death is necrosis due to number of unfavourable reasons in the cell.Necrosis is having both good and bad effects based on the type of cell it is .

Hello,

I would say that this definition gives a clear idea what necrosis is:

"Necrosis (from the Greek νεκρός, "dead") is the premature death of cells and living tissue. Cells which die due to necrosis do not usually send the same chemical signals to the immune system that cells undergoing apoptosis do. This prevents nearby phagocytes from locating and engulfing the dead cells, leading to a build up of dead tissue and cell debris at or near the site of the cell death. For this reason, it is often necessary to remove necrotic tissue surgically. "

Source: http://www.diffen.com/difference/Apoptosis_vs_Necrosis

Best regards

Then in plants, there is the phenomenon of hybrid necrosis, where the F1 progeny of a cross between two seemingly healthy individuals can show severe necrosis. I have unfortunately experienced it several times when making wide crosses in wheat: the parents are as green as can be but the F1 from the 2-3 leaf stage looks like somebody has sprayed it off with herbicide. It has been proposed in the literature as one of the mechanisms that underlies speciation, ie it prevents genetic exchange between genetically distinct individuals. It has been suggested that an interaction between complementary parental alleles in the F1 results in a release of reactive oxygen molecules within the tissue which do what they do best resulting in necrotic lesions. Certainly in wheat the severity of symptoms seem to be correlated to light intensity and temperature.

http://www.nature.com/nrg/journal/v8/n5/full/nrg2082.html

Dear Mohsen

Necrosis is the name given to un-programmed death of cells and living tissue.

It is less orderly than apoptosis, which are part of programmed cell death.

In contrast with apoptosis, cleanup of cell debris by phagocytes of the immune system is generally more difficult, as the disorderly death generally does not send cell signals which tell nearby phagocytes to engulf the dying cell.

This lack of signalling makes it harder for the immune system to locate and recycle dead cells which have died through necrosis than if the cell had undergone apoptosis. The release of intracellular content after cellular membrane damage is the cause of inflammation in necrosis.

There are many causes of necrosis including injury, infection, cancer, infarction, toxins and inflammation. Severe damage to one essential system in the cell leads to secondary damage to other systems, a so-called "cascade of effects".

Necrosis can arise from lack of proper care to a wound site.

Necrosis is accompanied by the release of special enzymes, that are stored by lysosomes, which are capable of digesting cell components or the entire cell itself.

The injuries received by the cell may compromise the lysosome membrane, or may initiate an unorganized chain reaction which causes the release in enzymes.

Unlike in apoptosis, cells that die by necrosis may release harmful chemicals that damage other cells.

Best Regards

In the field of medicine, necrosis is the pathologic death of one or more cells, or of a portion of tissue or organ, resulting from irreversible damage; earliest irreversible changes are mitochondrial, consisting of swelling and granular calcium deposits seen by electron microscopy; most frequent visible alterations are nuclear: pyknosis, shrunken and abnormally dark basophilic staining; karyolysis, swollen and abnormally pale basophilic staining; or karyorrhexis, rupture, and fragmentation of the nucleus. After such changes, the outlines of individual cells are indistinct, and affected cells may merge, sometimes forming a focus of coarsely granular, amorphous, or hyaline material.

Necrosis in the death of the tissues of the body and cannot be treated, the tissue may be removed, but it can not be returned to good health. Necrosis is caused by a lack of blood and oxygen to the tissue. It may be triggered by chemicals, cold, trauma, radiation or chronic conditions that impair blood flow. Necrosis is an expected effect of certain treatments such as radiation therapy. When the radiation is directed at a certain area, much of the tissue in that area will die or, in other words, undergo necrosis. One common type of necrosis is gangrene, which is often caused by damage from cold. There are many types of necrosis, as it can affect many areas of the body, including bone, skin, organs and other tissues.