Figure 3

Transmission electron micrographs of ultrathin sections of a 0 to 3 days posthatching larva of Wirenia argentea . A: Cross section through the abapical part showing the opening of the posterior invagination (arrow) to the outside; scale bar equals 20 μm. B: Detail from A showing the opening of the posterior invagination (arrow) to the outside; scale bar equals 5 μm. C: Part of a cross section through the abapical part somewhat more apical than in A showing the posterior invagination (arrow); scale bar equals 10 μm. D: Detail from C showing the posterior invagination (arrow); scale bar equals 1 μm. Abbreviations: c, calymma; hg, hindgut anlage; tr, trunk.