Haploid germ cell male

Perhaps the most important precaution to be observed in carrying out an autosomal recessive lethal test such as the one outlined above is to treat only the haploid gametic stages with the chemical mutagen. For if instead diploid germ cell stages are treated, recombination, which is normally absent in the male, may be induced by the treatment. Such induced recombination between homologous chromosomes could lead to deficient chromosomes, or still more complex aberrations, which could not be readily... 

Ponzetto, C., and Wolgemuth, D. J. (1985). Haploid expression of a unique c-abl transcript in the mouse male germ line. Mol. Cell. Biol. 5 1791-1794. 

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