ATROPHY, DEGENERATION, PIGMENTATION, AND NECROSIS. 



85 



MUCOUS DEGENERATION. 



Mucous degeneration may occur in cells or in intercellular substance. 

 When occurring in cells it consists, under pathological as under normal 

 conditions, of the transformation of the protoplasm into a translucent, 

 semi-fluid material, occupying more space than the unaltered protoplasm, 

 and hence causing a swelling of the cells (Fig. 22). This new-formed 

 material contains mucin in solution, which is precipitated by acetic acid. 

 It occurs under a variety of conditions, sometimes as an abnormal in- 

 crease of a normal function of cells, as in many catarrhs, sometimes as 

 an entirely abnormal transformation. The cells may be totally destroyed 

 by the accumulation of the mucoid material within them. 



In certain cases, as in many tumors, in cartilage, bone, and other tis- 

 sues, the intercellular substance may undergo conversion into mucin-con- 



FIG. 23. Mucous DEGENERATION OF FIBROUS TISSUE OF MAMMA. 



taiuiug material, losing almost entirely its original structure (Fig. 23). 

 The cells in such cases may be affected only secondarily by the pressure 

 which the new-formed material exerts upon them. 



TECHNIQUE. Tissues should be hardened in Orth's fluid or formalin, followed by 

 alcohol; the sections are stained with picro-acid fuchsin or with haematoxylin, which 

 colors the mucin-containing portions. 



COLLOID DEGENERATION. 



This is very closely allied, both in chemical and morphological char- 

 acters, to mucous degeneration, and in many cases there is no definite 

 microscopic distinction between them. But colloid material, which is 

 normally present in the thyroid, is firmer and more consistent than mu- 

 cous, does not yield a precipitate on addition of acetic acid or alcohol, 

 and its formation is usually confined to cells ; not involving intercellular 

 substance, except by an atrophy which its accumulation sometimes in- 

 duces. The cells may contain larger and smaller droplets of colloid ma- 

 terial, or the latter may nearly or entirely replace the protoplasm and 

 accumulate to such an extent as to cause rupture and destruction of the 



