Abstract
Twelve strains of primary trisomics were examined by the karyotype analysis. Four strains, B, C, E and H types were decided to have individual extra chromosomes K6, K12, K4 and K10 respectively. Between K5 and K9 and among K7, K8 and K11 chromosomes, there were some difficulties to discriminate each other. In well conditioned nuclei, however, K5, K7, K9 and K11 extra chromosomes were found to be carried by the A, D, L and F type trisomics respectively. Extra chromosome K8 was present in G, I, J and K type trisomics. Three kinds of extra chromosomes (K1, K2, K3) were not found in these 12 strains. Through the present study the modified technique for stretching the chromosomes appeared to be also promising to characterize chromosome bands.
