Table 2 (continued) 



Defect 



Cause 



Remedy 



Method of Prevention 



Sections contain 

 fine opaque 

 needles 



1. Imperfect 

 removal of 

 mercuric fixatives 



Return sections 

 through proper 

 sequence of re- 

 agfents to water. 

 Treat 30 min. 

 with Lugol's 

 iodine (see p. 

 12), rinse, and 

 bleach in 5% so- 

 dium thiosul- 

 phate. Restain 



1. Treat tissues as 

 indicated ou p. 12 

 before embedding 



Sections contain 

 black granules 



Long storage in 

 formaldehyde 



1. None 



1. Never store tissues 

 in formaldehyde — 

 always in paraffin 

 blocks 



