mo hr 
DEGENERATIVE CIANGES IN TISSUE. 
DEGENERATIVE CHANGES IN TISSUE. 
What is necrosis? Give some of its causes. 
Necrosis is the death of a circumscribed portion of tissue, and may 
result from insufficient nutrition, mechanical injury, extreme degrees 
of heat or cold, bacterial products, or from the action of destructive 
chemicals. 
What is the appearance of necrosed tissue microscopically ? 
It may show a mass of degenerated cells and cell detritus, or the 
tissue may be swollen, granular, and disintegrated. Finally the 
whole may form a mass of irregular granules with fat droplets, various 
forma of crystals, shreds of the more resistant tissues and bacteria 
mixed with them. 
How is coagulation necrosis produced, and how is the tissue altered 
microscopically ? ; 
When the blood supply is cut off from a portion of tissue surrounded 
by or continuous with healthy tissue, this “cut-off” area is one of 
“coagulation necrosis,” and a peculiar change takes place, in which the 
cells of the tissue are altered and appear under the microscope shining 
and translucent, diminished in size, sometimes altered in shape, and 
the nuclei have disappeared. 
What is the meaning of the term cheesy degeneration ? 
It is a term applied to a form of tissue degeneration, similar to the 
degeneration in coagulation necrosis. In the form of degeneration 
specified as cheesy, however, the dead tissue loses its structural features 
completely and becomes converted into granular, albuminous, and fatty 
material, which may disintegrate and soften or may dry and become 
dense and firm, or may become infiltrated with lime salts. 
What change takes place in parenchymatous degeneration or 
cloudy swelling ? 
The cells of organs or tissues that have undergone this change be- 
come swollen and so filled with albuminous granules that the original 
cell structure is entirely concealed. The gross specimen of such a 
degenerated tissue is of a dull-grayish appearance; it is swollen and 
less translucent than under normal conditions. 
What is fatty degeneration ? 
The protoplasm of a cell becomes converted into fat, at first, as 
little drops which coalesce to form larger ones, until finally the cell- 
protoplasm may be entirely replaced by fat. : 
