CHAPTER VII 



EFFECTS ON THE SKELETON 



It has long been recognized that the skeleton loses little or nothing during 

 general inanition, the wasting of other parts of the emaciated body giving rise to 

 the characteristic appearance expressed by the phrase "reduced to a skeleton" 

 (see Fig. 33). During certain types of partial inanition (rickets and scurvy), 

 however, the skeleton is markedly affected. After a brief summary, the effects 

 of inanition upon the skeleton will be considered under (A) total inanition, or on 

 water only, and (B) partial inanition. 



Summary of Effects on the Skeleton 



During total inanition (or on water alone) there is but slight loss in the weight 

 of the skeleton in adults, since the solids lost are largely replaced by water. 

 In the young, during incomplete inanition there is even a persistent skeletal 

 growth, variable in amount according to circumstances. 



Histologically there is but little change in the adult bony tissue during total 

 inanition, aside from resorption tending to osteoporosis in chronic conditions. 

 Degenerative changes may occur in the cartilage cells, and especially in the adi- 

 pose bone marrow, which undergoes mucoid atrophy (as described in Chapter 

 VI). There is also an atrophy of the red marrow, with degenerative changes in 

 the hemopoietic cells. Bone fractures heal poorly during inanition; but regen- 

 eration and restitution of normal skeletal structure occur upon appropriate 

 refeeding, if the preceding inanition is not too prolonged or severe. 



Protein Deficiency, including pellagra, tends to produce in adults a skeletal 

 condition of osteoporosis, somewhat similar to that in chronic total inanition. 

 In young animals on incomplete protein diets there appears to be less tendency 

 to persistent dystrophic skeletal growth, but more perfect recovery upon refeed- 

 ing after long periods of suppressed growth. 



Calcium and Phosphorus. — The skeleton serves as a storehouse of reserve 

 mineral supply, and is especially sensitive to a dietary deficiency in salts of 

 calcium or phosphorus. A deficiency in calcium or phosphorus alone apparently 

 produces skeletal softening grossly resembling rickets, but histologically 

 presenting a "pseudorachitic osteoporosis" of variable extent and character. 



True rickets apparently involves an accessory factor ("fourth vitamin") 

 and also a relative deficiency in calcium or phosphorus. The fresh weight of 

 the skeleton is not much affected, but there is marked softening (with conse- 

 quent deformities) and the dry weight is greatly reduced. Histologically 

 rickets is characterized, in the region of enchondral ossification, by an increased 

 width and irregularity of the proliferative cartilage zone, a failure of the pro- 



133 



