Fig. 6

The formation of carapace in Cypripedium formosanum seeds. A Light micrograph showing a cross-section through a developing seed at the globular stage. The embryo is enclosed by the inner seed coat (arrowhead) from the inner integument. The tangential and radial walls of the outer seed coat (arrow) have thickened. Scale bar = 30 μm. B Light micrograph showing the fluorescence pattern of a cross-section through a developing seed at the stage similar to A after the Nile red staining. The surface wall of the embryo proper possesses fluorescent signals (double arrowheads). In addition, the tangential and radial walls of the outer seed coat (arrow) and the inner and outer surface walls of the inner seed coat (arrowheads) fluoresce brightly. Scale bar = 30 μm. C Electron micrograph showing the adjoining region of the embryo proper cell and the cell of the inner seed coat at the globular stage. Osmiophilic lipid bodies (OL) have accumulated within the embryo proper cell (EP), and a distinct osmiophilic layer (arrowhead) is present in the inner surface wall of the inner seed coat (IS). N, nucleus. Scale bar = 2 μm