82 ATROPHY, DEGENERATION, PIGMENTATION, AND NECROSIS. 



connective tissue 1 in a manner identical with that in which the normal 

 pauniculus adiposus is formed. The heart muscle or the gland cells are, 

 lender such conditions, affected secondarily through pressure atrophy 

 from the accumulated fat. 1 It should be remembered that fatty infiltra- 

 tion and fatty degeneration may occur simultaneously. When fat pro- 

 duction or fat storage is largely in excess of fat consumption, either from 

 local or general causes, the condition is called lipomatosis. 



TECHNIQUE. Fatty tissues may be teased fresh in salt solution; or they may be 

 hardened in Flemming's osmic acid solution (see page 53) in preparation for sectioning 

 Hardening in Orth's fluid and afterward in alcohol gives good results if the lesion be 

 extensive. In tissues which have been soaked in alcohol the fat is no longer present, 

 its former seat being indicated by clear spaces filled with the mounting medium. Fat 

 crystals, however, often persist after prolonged soaking in alcohol. 



AMYLOID DEGENERATION (Waxy or Lardaceous Degeneration). 



This is a process by which the basement substance of various forms 

 of connective tissue, and especially the walls of the blood-vessels, be- 

 come swollen and thickened by their conversion into ajtra2isjiiciinj,Jirm^ 



glassy, Colorless material, albj^iu'i nin^s_ 

 ^ x^. ; X ' .:..-.'"'* -" '-v^i' 1 '- yji character. This albuminous ma- 



terialmaybe p resent~in~FFle~tTssues~m 

 such small amount as to be recogniz- 

 able only under the microscope, or 

 it may be so abundant as to give a 

 very characteristic appearance to the 

 tissue. Parts in which the lesion is 

 marked are usually larger and contain 

 less blood and feel harder than nor- 

 mal, and have a peculiar shining and 

 translucent appearance which -varies 

 in character, depending upon the ex- 

 tent and distribution of the degener- 

 ated areas and upon its association 

 with other lesions, such as fatty 

 degeneration. It most frequently 

 occurs in the smaller arteries and 

 capillaries (Fig. 18), whose lumen is 



A, Waxy capillaries stained red ; B, normal capil- 

 laries, encroached upon by the thickening 



of the walls which the process in- 

 volves. It is usually the media and intermediary layers of the intima 

 which are earliest and most extensively affected. The change also often 

 occurs in the interstitial connective tissue and membranse propriae of 

 organs and in reticular connective tissue. It is both asserted and denied 

 that it may affect the parenchyma cells of organs. We have not been 

 able to find unmistakable evidence of its occurrence in parenchyma 



1 For a study of the deposition of fat in cells, see Arnold, Virch. Arch., Bd. 163, p 

 1, 1901. 



FIG. 18. AMYLOID DEGENERATION OF CAPIL 

 LARIES OF A GLOMERULUS IN THE KIDNEY. 



