104 



Microscopic Histochemistry 



of the chemical background nor the specificity of the results 

 has been tested so far. 



E) Lipid aldehydes. -hi 1924 Feulgen and Voit,^^ while 

 studying the nucleal reaction in HgCl2-fixed tissues, noticed 

 a widespread staining of elastic membranes and various cy- 

 toplasmic structures by SchifF's reagent, even without pre- 

 ceding acid hydrolysis. Staining could be prevented by pre- 

 treatment with phenylhydrazine. Obviously, the reaction was 

 due to some hitherto undescribed aldehyde to which they 

 gave the name of "plasmal," and the unknown compound 

 from which it is set free by HgCl2 they called "plasmalogen." 

 Further studies by Feulgen and his group^^ gradually suc- 

 ceeded in unraveling the nature of these mysterious sub- 

 stances. Plasmalogen turned out to be a new type of com- 

 pound, an acetalphosphatide. Acetalphosphatides resemble 

 lecithin or cephalin except for the fact that they contain only 

 one molecule of fatty aldehyde per molecule of glycerol, and 

 the linkage between the fatty aldehyde and glycerol is of the 

 cyclic acetal type. 



alpha-Lecithin 

 H2C— 0— O— C— R 



HC— O— O— C— Ri 



HoC — — P — choUne (or colamine) 



OH O 



(R and Ri, fatty acid radicals) 



alpha-Acetalphosphatide 

 H2C— 0\^ 



:CHR 



HC— O. 



HoC — O — P — choline 



/ N^ (or colamine) 

 OH O 



49. Feulgen, R., and Voit, K.: Arch. f. d. ges. Physiol., 206:389, 1924. 



50. Feulgen, R., and Imhauser, K.: Biochem. Ztschr., 181:30, 1927; Im- 

 hauser, K.: Biochem. Ztschr., 186:360, 1927; Voss, H.: Ztschr. f. mikr.-anat. 

 Forsch., 10:583, 1927; Behrens, M.: Ztschr. f. physiol. Chem., 191:183, 

 1930; Feulgen, R., and Behrens, M.: Ztschr. f. physiol. Chem., 256:15, 

 1938; Feulgen, R., and Bersin, T.: Ztschr. f. physiol. Chem., 260:217, 1939; 

 Voss, H.: Ztschr. f. Zellforsch. u. mikr. Anat., 31:43, 1940-41; Bersin, T., 

 Moldtman, H. C, Nafziger, H., Marchand, B., and Leopold, W.: Ztschr. f. 

 physiol. Chem., 269:241, 1941. 



