Cell differentiation in isolated inner cell masses of mouse blastocysts in vitro: onset of specific gene expression.
Inner cell masses (ICMs) were isolated by immunosurgery from giant blastocysts formed by the aggregation of three morulae. A layer of endoderm cells formed on the outer surface of these primary ICMs in vitro. When this layer was removed by immunosurgery, a secondary endoderm layer formed. Alphafetoprotein (AFP) was used as a biochemical marker to characterize visceral endoderm formation in these cultured ICMs. The immunoperoxidase reaction on sections of ICMs cultured for intervals up to 120 h in vitro showed that some primary endoderm cells contained AFP, but these were always in the minority. The secondary endoderm layer, on the other hand, was composed of predominantly AFP-positive cells. It is concluded that the primary endoderm contains mainly parietal endoderm cells, while the secondary layer contains visceral endoderm cells. A model is proposed for the consecutive differentiation of parietal and visceral endoderm cell types from the ICM of mouse blastocysts.
D000818:Animals; D001755:Blastocyst / Q000166:cytology* / Q000378:metabolism; D002454:Cell Differentiation; D004707:Endoderm / Q000166:cytology* / Q000378:metabolism; D051379:Mice; D008954:Models, Biological; D000509:alpha-Fetoproteins / Q000096:biosynthesis*
D000509:alpha-Fetoproteins