Figure 4.

Survey of entire human embryonic stem cell (hESC) culture from LRB03 embedded at culture day 32 with neighboring sections stained for OCT4 (A), p63 (B), nestin (C), and YKL-40 (D). Boxed areas are shown at higher magnification in Figure 5. (A) Small OCT4-positive areas are distributed widely across the entire culture (arrowheads) in contrast to the vast OCT4-negative areas. (B) Ectodermal marker p63 is positive in well-defined regions of the culture, with a distinct borderline to OCT4 areas (arrows), but this is better appreciated at higher magnification (Fig. 5B). (C) A moderate nestin-positive staining is seen in areas overlapping the OCT4 stained areas (arrowheads). The stronger nestin-reacting subregions of the culture are not OCT4 positive (see also Fig. 5C). (D) YKL-40 is present in all regions and subregions throughout the culture, both in the pluripotent OCT4-positive cells and in the various progenitor cells. YKL-40 reactivity is also seen in structures that show no OCT4, p63, or nestin reactivity (see encircled area). A–D: same magnification, scale bar: 1 mm.