Fig. 6.

PCD during tracheo-oesophageal separation at E11.5 and E12.5: effect of Adriamycin and loss of Nkx2.1 or Apaf1 function. (A–W) Immunohistochemistry for activated caspase 3 on transverse sections through the foregut of E11.5 saline-treated (A–G; n = 6), Adriamycin-treated (H–N; n = 6) and Nkx2.1^−/− (O–U; n = 3) embryos, and of E12.5 Apaf1^+/+ and Apaf1^−/− embryos (V,W; n = 3). Sections are from levels indicated on the schematic representation. (A¹–N¹) Templates used to illustrate spatial PCD patterns as described in Fig. 5. Horizontal lines define foregut zones for calculation of PCD index (see Fig. 7). Arrows in (E, E¹) indicate the concentration of apoptotic cells in epithelial ridges immediately cranial to the point of foregut separation, a finding that is not seen in either Adriamycin-treated (L, L¹) or Nkx2.1^−/− (R–T) embryos. Arrowheads in (M¹,N) show apoptotic cells in the dorsal mesenchyme associated with a cellular condensation. Arrowheads in (O–U) highlight excessive apoptosis in Nkx2.1^−/− embryo. Circles in (V,W) highlight the separated trachea and oesophagus in Apaf1^+/+ and Apaf1^−/− embryos. Abbreviations as in Figs. 3, 4 and5. Scale bar (in A): 50 μm for all parts.