Figure 1

Widefield visualisation of Y positive donor-derived cells and expression of CD45 and cytokeratin fall into four classes. CD45 positive stained cells (CY3-red) were identified on tracheal sections, photographed, and their positions recorded. The CD45 signal was lost in subsequent manipulations. Sections were then subjected to Y chromosome FISH (Tx-Red) and immunohistochemistry for cytokeratin (FITC-green). Donor-derived (Y FISH positive) cells fell into four classes (Table 2). Figure 1A shows a CD45 positive (i) and cytokeratin positive (ii) coincident cell arrowed; CD45 positive (iii) and cytokeratin negative (iv) coincident cell arrowed; CD45 negative (not shown) and cytokeratin positive (v,vi,vii,viii); CD45 negative (not shown) and cytokeratin negative (ix, x) arrowed cells. ix also contains a cytokeratin positive cell marked with an arrowhead. 1B top panel shows two CD45 positive (i) and cytokeratin positive (ii) cells and the brightfield staining of this tracheal section (iii) with cells marked with arrows; Figure 1B bottom panel shows a CD45 positive (iv), cytokeratin negative (v) cell and photomicrograph (vi) shows brightfield staining of the same region with the cell marked with arrowhead. Additional file 4 shows cytokeratin staining alone of tracheal sections and also cytokeratin staining after Y chromosome FISH illustrating that the distribution of cytokeratin staining is the same. Scale bar 5 uM.