The wild-type unpollinated Arabidopsis pistil was fixed with 4% paraformaldehyde (w/v) for 1 h and then cleared in ClearSee.v2 solution for 4 weeks. To observe the internal structure of the pistil, it was stained with 0.1% (w/v) calcofluor staining solution after clearing. This two-photon image was taken using a two-photon excitation microscope (A1R MP, Nikon) at an excitation wavelength of 850 nm. It shows the longitudinal optical section of the ovary, including each side of the ovary wall, the central transmitting tract, and the vertically aligned ovules on both sides of the transmitting tract. The width of this image is approximately 500 µm.
Yoko Mizuta (Wed,) studied this question.