Polytene chromosomes in mouse trophoblast giant cells

摘要: Mouse trophoblast giant cells undergo successive rounds of DNA replication resulting in amplification the genome. It has been difficult to determine whether cell chromosomes are polyploid as liver or polytene Dipteran salivary glands because do not condense. We have examined pattern hybridization mouse with a variety situ chromosome markers address this question. Hemizygous displayed one signal per nucleus both diploid and cells, while homozygous two signals types. These patterns consistent cytological evidence indicating that rather than polyploid. However, contrast situation glands, homologues appear be closely associated. conclude mechanism involves multiple absence karyokinesis cytokinesis, sister chromatids, but homologous chromosomes, remain associated during process.