68 MICROSCOPIC TECHNIQUES 



Cowdry Modification of Feulgen Reaction for Paraffin 

 Sections of Animal Tissues 



SPECIAL REAGENTS 



Sublimate-Alcohol Fixative. Combine equal vol. saturated mercuric 



chloride soln. and absolute alcohol. 

 1 N Hydrochloric Acid. 

 Feulgen Reagent. See page 67. 

 Sodium Bisulfite Solution. Add 30 ml. 1 M sodium bisulfite soln. 



to 600 ml. tap water. 



PROCEDURE 



1. Prepare paraffin sections of tissue fixed in the sublimate- 

 alcohol fluid. 



2. Pass through graded alcohols to water and place in the hydro- 

 chloric acid for 1 min. 



3. Place in another portion of the acid at 60° for 4 min. 



4. Treat with the Feulgen reagent for about 1.5 hr. The time may 

 have to be varied to suit the particular sections used. 



5. Pass through three separate portions of the sodium bisulfite 

 soln. leaving in each for 1.5 min. and agitating frequently. 



6. Wash for 5 min. in tap water. 



7. Dehydrate, clear, and mount in balsam. 



Oster Modification of Feulgen Reaction for Fresh-Frozen 

 Sections of Animal Tissues 



SPECIAL REAGENTS 



1 % Mercuric Chloride. 



Feulgen Reagent. See page 67. 



0.01 N Hydrochloric Acid Containing 1 % Sodium Bisulfite. 



PROCEDURE 



1. Cut 50 /x sections of fresh tissue on a freezing microtome. (The 

 sectioning should be carried out within 2-3 hr. after the death of the 

 animal and removal of the tissue. Until ready for use, keep the tissue 

 before cutting, and the sections after cutting, in physiological salt 

 solution.) 



2. Place the sections in 1 % mercuric chloride for 5 min. in order 

 to liberate free aldehyde from "plasmalogen." Wash with water. 



