Abstract: The mitotic chromosomes of silkwormBombyx mori are prepared from gonads of fourth or fifth instar larvae 14 h after BrdU (5-bromo-2'-deoxyuridine) solution has been injected into the silkworm hemolymph. With the fluorochrome (FPG) banding technique, the replication banding patterns of silkworm mitotic chromosomes during theearly, mid and late replications are successfully demonstrated. When BrdU incorporates into DNA synthesis early, the early replication banding pattern, showing large lightstained area on most chromosomes, can be observed. According to the characteristics of replication bands in each chromosome, homologous chromosomes can be identified;When BrdU incorporates into DNA synthesis at mid-way, the mid replication banding pattern, which displays more bands, can be observed; When BrdU incorporates intoDNA replication very late, only a few light-stained bands can be found near the terminal or middle area of some chromosomes. This kind of pattern is classified as late replication bading pattern.

Key words: silkworm, chromosome, replication banding pattern