A Rigorous Re-Definition of the Piasmal Reaction

Abstract

The plasmal reaction is here modified so that it is made strictly specific for acetal lipids alone. The two essential points in making such specificity possible are: (1) limiting the duration of the action of HgCl2 to 2-10 minutes, thus insuring that neither acid hydrolysis nor oxidation participates in the unmasking; (2) obtaining negative controls upon sections of the same block of tissue, these being treated identically in all respects except that immersion in HgCl2 is omitted. Lipids positive under these conditions are acetals but not necessarily acetal phospholipids. In. order to satisfy the second criterion above, material must be either unfixed or fixed for only 1-6 hours in formol. Longer fixation in formol both destroys the acetals and unmasks some non-acetal lipids.