Fig. 4. Emigration of graft cells into the host: GFP to 0, 55 days p.o. The border between the host gastrocnemius (h, left) and the grafted anterior tibial muscle (g, right) is shown. (A) Fluorescence shows GFP. (B) The adjacent section is haematoxylin/eosin-stained, with contours to show GFP-positive fibres. Inset, enlargement of the framed region to show that there are no central nuclei in the GFP-positive fibres. (C) Region of host with GFP-positive fibres. (D) Same region as in C, with SDH staining to show fibre types and black contours to indicate GFP-positive host muscle fibres. Insets in C and D, with comparable regions in the contralateral leg to which no GFP-positive TA had been grafted, to show lack of autofluorescence of oxidative fibres. In C', blue fluorescence indicates Hoechst-stained nuclei, and in D', SDH enzyme histochemistry indicates a fibre-type pattern. Bar, 100 µm.