SMEAR METHOD FOR CHROMOSOME PREPARATIONS 



133 



c. Solid Tissues : The specimen may be embedded and cultured in a plasma clot 

 (see Harnden I960) or digested with trypsin, the resulting suspension being cul- 

 tured (see Puck et al, 1958). In either case, subcultures are grown on coverslips 

 or slides, to which the cells remain attached during all treatments. The cells 

 can be cultured for weeks or months. Colchicine is usually added for the last 

 4-6 hours, to provide metaphase figures, and is followed by hypotonic citrate, 

 fixation, air-drying and staining (as above). 



2. MEIOTIC CHROMOSOMES : The testis is the only practical source of meiotic chro- 

 mosomes. Small fragments of the testis are placed, immediately upon removal, in 

 hypotonic saline or citrate, and the tissue is teased apart. Fixation is in acetic al- 

 cohol, followed by bulk Feulgen staining, and squashing of tiny fragments beneath a 

 siliconized coverslip as in the manner described above. For examination of chro- 

 mosomes at phases other than metaphase, hypotonic pretreatment should be omitted. 

 However, the spreading of the chromosomes is then much less satisfactory (see Ford 

 & Hammerton, 1956) 



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4 m 



10 II 



13 14 



16 



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IS 

 18 



XX ;<x AA aa 



19 20 21 22 





CHROMOSOMAL COMPLEXES OF THE HUMAN MALE AND FEMALE 



(Courtesy of Drs. O ]. Miller and W. R. Breg, pre-publication permission) 



