In addition to the morphological, skeleton and biometric characteristics, kariological study is the key to the animal identification and classification. Due to the insufficient studies on amphibian in khorasan Province (Iran), this research atudies five areas of this province, namely Mashhad, Sarakhs, Bojnoord, Shirvan and Tibad. Totally, 100 samples were collected in these regions from April to November, which were transfered alive to the lab. In the labaratory, the vimnoblastin was in jected to the samples proportional to their weights and consequently, the bone marrows were extracted. The obtained solution was dropped from a height of 60 to 70 cm on the frozen slides placed on an inclined surface. Prepared slides were stained and photographed to study the chromosomes. Relative lenght and arms ratio of chromosomes were used to recogonize the centromere position and chromosomal type. finally, based on the above studies the related idiograms were derived. This research illustrates that all frogs have a set of 26 (2n=26) chromosomes and all toads have a set of 22 chromosomes. It is concluded that all collected frogs and toads from the different stations are Rana ridiunda and Buffo viridis species, respectively. This research shows no sex domophism in all samples.

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