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INVESTIGATION OF POSSIBLE AGE EFFECTS ON MEIOTIC CHROMOSOMAL RECOMBINATION AND SEGREGATION IN ARMENIAN HAMSTER SPERMATOCYTES
Citation:
Allen, J.W. AND C. Gwaltney. INVESTIGATION OF POSSIBLE AGE EFFECTS ON MEIOTIC CHROMOSOMAL RECOMBINATION AND SEGREGATION IN ARMENIAN HAMSTER SPERMATOCYTES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-85/346 (NTIS PB86175411).
Description:
Male Armenian hamsters (Cricetulus migratorius; 2N:22) were evaluated for age effects upon meiotic recombination and aneuploidy incidence. Primary spermatocytes from young and old animals revealed similar chiasma frequencies. The incidence of terminal-type chiasmata in sex bivalents was also measured and determined to be unaffected by age. Percentages of univalents and of hyperploid metaphase II cells were evaluated by chromosome groups, based upon individual chromosome morphologies. Regardless of age, the larger dichiasmate chromosomes were seldom observed as univalents, or as extra chromosomes in hyperploid cells. The monochiasmate small autosomes and sex chromosomes were noted with frequencies approximating 5.5 - 6.5% in animals from both age groups. However, only the small autosomes appeared to be significantly implicated in hyperploidy. Although still a rare event, metaphase II hyperploidy was significantly increased in older animals (0.9% incidence in young; 2.4% in old).