Evaluation of its performance in identifying chemical mutagens and carcinogens

Carcinogens induce reversion of the mouse pink-eyed unstable mutation

“…EMS, MMS (54), as well as BaP (38), which otherwise are potent mutagens, are negative in the mouse-specific locus test. In the mouse spot test, x-rays, EMS, MMS, ENU, BaP, and TCE give positive result (39). Thus, the majority of chemicals that were positive for p un reversions were also positive in the mouse spot test.…”

In Vivo Genotoxicity Assays

“…The mouse spot test is an in vivo assay capable of detecting genetic effects of several kinds, including intragenic mutations, minute defi ciencies, deletions (through breakage or nondisjunction) of various amounts of chromosomal material, and somatic crossing -over [144,145] . The assay involves treatment of mouse embryos, which are heterozygous for different recessive coat color genes and are treated in utero at gestation day 9 -11 with the test substance.…”

“…The assay involves treatment of mouse embryos, which are heterozygous for different recessive coat color genes and are treated in utero at gestation day 9 -11 with the test substance. The exposed embryo at gestation day 10 contains about 150 -200 melanoblasts and each melanoblast has 4 coat color genes that are studied [145,146] . The in utero exposure may result in an alteration or loss of a specifi c wild -type allele in a pigment precursor cell, resulting in a color spot in the coat of the adult animal.…”

“…The in utero exposure may result in an alteration or loss of a specifi c wild -type allele in a pigment precursor cell, resulting in a color spot in the coat of the adult animal. The frequency of spots is compared with the frequency in negative controls [145,146] . In the mouse spot test there are four possible mechanisms by which the recessive coat color alleles can be expressed: gene mutation in the wild -type allele, defi ciency (large or small) of a chromosomal segment involving the wild -type allele, nondisjunctional (or other) loss of the chromosome carrying the wild -type allele, and somatic recombination (using a marker gene that then becomes homozygous after recombination).…”

“…The test was suggested as a complementary in vivo test to the bacterial mutagenicity assay for detection of mutagenic substances and as a confi rmatory test for the identifi cation of carcinogens [145] . However, the infrequent use of the spot test may partly be due to considerations of cost effectiveness and the number of animals needed for testing and also for toxicological considerations.…”