CYTOGENETIC ANALYSIS 



489 



Squash technique for chromosomal analysis 



1 . Transfer the cover glass upright with forceps and place upon a pedestal (30 x 

 60 mm. vial), as depicted in figures 67 and 68. 



2. Add 3 drops of 1 to 1| per cent acetocarmine or propionocarmine to the upper 

 surface of the cover glass. 



3. Touch the tip of an eyedropper or dip-stick retained in the iron mordant 

 concentrate to the stain to deposit a very small amount (■£ drop or less). 



Fig. 67. Illustration of various steps in squashing procedures. 



A. Pretreatment(s) and Fixation 



^=V 



I"- "™1 



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Seal 



Method of G. Yerganian and associates. Refer to figure 68 for layout of instruments 

 and chemicals. 



4. Lift cover glass with forceps and tilt back and forth to disperse the mordant 

 throughout the stain, covering the entire surface of the cover glass. A purple hue will 

 be seen to spread over the entire area. Place atop the pedestal and wait 20-30 seconds 

 (phase-contrast microscopy), or 60-90 seconds (bright-field microscopy) before 

 proceeding. 



5. Decant (into vial) the now purple (overmordanted) stain and reset atop the 

 pedestal. Rinse with several drops of dilute acetocarmine or propionocarmine and 

 decant. Dilute stain is readily made available by simply redissolving the stain-mash 

 that accumulates onto the filter paper (following the initial filtration) in a similar 

 volume of 45 per cent acid and refiltering. Straight 45 per cent acetic acid may act 



