Iron Hematoxylin-stained Testis 231 



various percentages of alcohols, dehydrated, cleared, and mounted in 

 balsam in the usual manner. A section on a slide, which is required for 

 examination over a long period of time, should be some distance from the 

 edge of the coverslip, for, as the balsam oxidizes inward from the edge, 

 it tends to remove the color of the stain from the chromosomes, leaving 

 them a rather unpleasant shade of brown. If this happens to a valuable 

 slide, however, the matter can be remedied by the utilization of a green 

 light which will make the chromosomes appear black again. 



SUMMARY 



1. Remove the testes from the scrotal sac of a young male rat and trim 

 away the epididymis. 



2. Slash the testes deeply with a razor, making cuts 2 or 3 mm apart. 

 Fix in at least 100 ml of Allen's fluid from 1 to 7 days. 



3. Wash for about 1 hr in running water before removing small pieces 

 to 70% alcohol. Change alcohol daily until no further color comes away. 



4. Dehydrate, clear, embed in wax, and cut 5-fi sections. Attach sections 

 to slide. Dewax dried slides and grade down to water through usual 

 reagents. 



5. Mordant overnight in 2.5% iron alum. 



6. Rinse briefly and stain overnight in 0.5% hematoxylin. 



7. Rinse briefly and place in 2.5% iron alum until chromosomes are 

 clearly differentiated. 



8. Wash in alkaline tap water until sections are blue. Dehydrate, clear, 

 and mount in the usual manner. 



