Calomys LauchaChromosome (Rodentia, Cricetidae) from Uruguay and Argentina

Abstract
Forty five specimens of Calomys laucha (Olfers, 1818) from Uruguay and Argentina localities, were analyzed. A diploid number 2n; = 64:NF = 68 was found. Heterochromatic blocks were located in the centromeric regions. G-banding pattern and distribution of silver stained material (NORs) were also examined. Analysis of spermatogenesis stages was performed doing emphasis on the sex chromosome behavior.