Spatial distribution of transcripts of the long repeated ETn sequence during early mouse embryogenesis.

Abstract
RNA-DNA in situ hybridization revealed a high level of ETn (early transposon) transcripts in the pluripotent cell lineage of the 3.5-7.5-day mouse embryo. Some extra-embryonic ectoderm derivatives also show a high level of ETn transcripts at these stages. Older embryos (8.5 days and later) have a uniform low level of ETn transcripts.