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Figure 4: Internal organs can be viewed in both opaque, uncleared and in cleared embryos. In an uncleared embryo stained for pax2 at stage 34 (A), the optic stalk (yellow arrow) can be visualized relatively easily as can the staining down the neural tube. However, details are not sharp. By clearing the embryo (B) the boundaries of expression sites, including the optic stalk (yellow arrow) are sharper. The extent of clearing is shown by the ability to see both eyes in this cleared embryo. Also note that some staining has accumulated in the internal cavities (purple arrow), a common problem when viewing cleared embryos. |