THE STAINING AND CHROMIUM BINDING OF RAT BRAIN TISSUE AND OF LIPIDS IN MODEL SYSTEMS SUBJECTED TO BAKER'S ACID HEMATEIN TECHNIQUE

Abstract

From experiments with saturated and highly unsaturated lecithin it was concluded that the presence of ethylenic double bonds is not imperative for the color development in Baker's acid hematein technique while it does affect the amount of churomium bound. Except for choline-containing phospholipids that yield the strongest staining, other lipids were also found to be colored, although to a lower degree. These staining characteristics could not account for the great differences in staining properties of white and gray matter of rat brain since, as was previously found, both types of tissue contain practically the same amounts of phospholipids on a dry weight basis. In the present study equal concentrations of chromium were detected in a number of hypothalamus regions after hot chromation of the tissue. The regions investigated were: chiasma opticum, area anterior, nucleus supraopticus and nucleus paraventricularis. On the basis of these and other findings it was concluded that the Baker technique should be considered as a means for detecting polar lipids in a particular physicochemical state (smectic mesophase or myelin structure) rather than specifying the type of the lipid. An alternative or complementary explanation may be given by assuming a further reduction in unstainable tissues and cells of the reactive reduced form of hexavalent chromium—Lillie assigned the binding of acid hematein to tetravalent chromium—to trivalent chromium which does not bind hematein under acidic conditions.