CHAPTER XVII 



CALCIFICATION, CONCRETIONS, AND INCRUSTATIONS 



CALCIFICATION' 



Pathological calcifioation occurs in two forms: one is a precipita- 

 tion of calcium in secretions and excretions of the body; the other 

 is the deposition of calcium salts in the tissues themselves. The 

 former, which includes not only concretions in general, but probably 

 also the deposition of calcium salts in the cells and tubules of the 

 kidney,- both in disease and in experimental calcification after cer- 

 tain poisonings, is readily enough explained in most instances by rec- 

 ognizable alterations in the composition of the secretions, which lead 

 to simple chemical precipitations. With this form we shall deal in 

 the subsequent consideration of concretions, but, in referring to calci- 

 fication, shall indicate only depositions from the blood directly into the 

 tissues.^ 



Relation of Calcification to Ossification. — In normal ossification we have to 

 deal with the accumulation of lime salts within the stroma or cells of a tissue 

 that has usually undergone certain preparatory changes in the way of formation 

 of a more or less homogeneous ground substance, but has not suffered a total loss 

 of vitality, although vitality is possibly decreased. Pathological calcification is 

 similar, in so far as we have to deal with deposition of quite the same salts in tis- 

 sues that have suffered either total or partial loss of vitality, and which very 

 frequently indeed are hyaline. What appear to be essential differences are these : 

 (1) In calcification the lime salts always remain in clumps and masses, often 

 fusing to greater or less degree, but never with the diffuse even permeation of tissue 

 seen in ossification. (2) All the cells within a calcified area, if not dead at the 

 beginning of the process, eventually disappear for the most part, and we have 

 sooner or later a perfectly inert mass, practically a foreign body, instead of a 

 specialized tissue as in ossification. (3) Ossification is accomplished only in 

 varieties of connective tissue, but calcification may involve any sort of cell or 

 tissue provided it is degenerated sufficiently. Furthermore, anj^ area of calcification 

 is likely to be replaced by bone, no matter what tissue may be involved; ap- 

 parently the presence of calcium salt deposits in any part of the body can stimu- 

 late the connective tissues to form bone,* but in the absence of calcium salts even 

 the cells which are normally osteogenic will not form bone. 



1 Literature and resum6: Pfaundler, Jahrb. f. Kinderheilk., 1904 (60), 123; 

 Wells, Jour. Med. Research, 1906 (14), 491, and Arch. Int. Med., 1911 (7), 721; 

 Hofmeister, Ergebnisse Phvsiol., 1910 (9), 429; Schultze, Ergebnisse Pathol., 

 1910, XIV (2), 706. 



2 See Wells, Holmes and Henry, Jour. Med. Research, 1911 (25), 373. 



^ Normally the calcium content of the blood is quite constant, about 9-11 mg. 

 per 100 c.c. serum, and the quantit}' is not modified by most diseases, except 

 nephritis in which the serum calcium is reduced; also in eclampsia, tetany and 

 jaundice. (Halverson, Mohlcr and Bergcim, Jour. Biol. Chem., 1917 (32), 171.) 



* See Nicholson (Jour. Path. Bact., 1917 (21), 287) concerning heterologous 

 ossification. 



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