100 



CELL HEREDITY 



Chromosome 1 

 Chromosome 2 

 Chromosome 1-2 

 Chromosome 2-1 



Parental chromosomes before 

 duplication and pairing 



Actual pachytene 



configuration of a 



translocation heterozygote 



(b) 



Pachytene pairing 

 schematic configuration 



(c) 



1-2 



2 



A 



2-1 



Alternate 

 diS)unction 



Adjacent 



disjunction. 



type 1 



Adjacent 



disjunction, 



type 2 



ai 



3^ 



ai 



(d) 



FIGURE 4.4. Translocation heterozygote paired at pachytene. 



(o). Parental chromosomes are shown before duplication and pairing in meiotic 

 prophase. In the reciprocal translocation between chromosomes 1 and 2, each 

 chromosome is numbered with the sector containing the centromere given first. 



(b). An actual pachytene configuration redrawn from a photograph shows pairing 



