Figure 6
ICM lineage segregation during bovine blastocyst formation. (a) presents a single optical section through an ICM of bovine early blastocyst (7dpi) immunostained for NANOG and OCT4. The boxed areas are enlarged in the bottom row. NANOG shows nuclear and OCT4 sub-nuclear localisation in ICM White arrows indicate cytoplasmic localisation of NANOG and OCT4 in the trophoblast cells in the vicinity of the ICM. Confocal sections were taken every 2 μm (b) shows a 3-D reconstruction of confocal images of an early blastocyst (7/8dpi) double labelled for CDX2 and OCT4. OCT4 was predominantly located in the ICM, but some signal was detected in the TE cells. Dashed circle marks the ICM. (c) is a 3-D compilation of optical sections taken through hatching blastocyst (8/9dpi) labelled for NANOG and OCT4. Dashed circle marks the ICM. (d) shows a 3-D reconstruction composed of 30 confocal sections (taken every 3 μm) through bovine hatched blastocyst (9dpi) double labelled for CDX2 and OCT4. At this stage OCT4 positive cells entirely segregate to the ICM. CDX2 becomes restricted to the trophoblast. DAPI marks chromatin. Confocal sections were taken every 3 μm.