MEDICAL AND BIOLOGICAL STAINING TECHNIQUES 



2. Fill the mould with molten paraffin wax; then place the 

 object in the wax and arrange it so that it is set in the right plane 

 for sectioning. 



3. When the wax block so formed is partially set, immerse it 

 gently, while still in the mould, in cold water to ensure rapid 

 cooling and thereby obviating crystallization of the wax and conse- 

 quent crumbling of the block when it is mounted on the micro- 

 tome and sections are cut. 



Cutting of Sections 



This can only be learnt by practical experience under skilled 

 guidance in the laboratory, and it is not proposed to make any 

 attempt to deal with the subject here since space does not permit a 

 description of the various types of microtomes available and the 

 technique of manipulating them. However, readers would find the 

 chapter on section cutting in Histological TechniquCy by H. M. 

 Carleton and E. H. Leach (published by Oxford University Press), 

 very informative. 



Mounting Sections on Slides and Hydrating 



1. Wet the tip of the finger slightly with glycerine albumen 

 (Mayer) and make a smear over an area large enough to take the 

 section in the centre of the slide. 



2. Pick a section up with a needle or forceps and place it over 

 the smear of albumen. 



3. With the thumb, gently press the section on to the smear so 

 that it is quite flat and without folds or creases, taking care not to 

 damage the section in the process. 



Note: If the sections are curled up or folded, first place a drop of 

 1% potassium dichromate on the slide and float the section on 

 this; then heat very gently until the section floats out flat. Blot 

 round the edges of the section to remove excess solution; then 

 carefully but thoroughly blot until all traces of liquid are removed. 

 Leave the slide on a warm surface for a few minutes to drive away 

 the last traces of water ; then proceed as follows : 



4. Gently warm the slide until the paraffin wax just melts; then 

 wash away all traces of wax with two or three changes of xylol. 



5. Remove the xylol by washing the preparation thoroughly 

 with absolute alcohol. 



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