Fig. 6.

Visualization of β-actin mRNA by three-dimensional digital imaging microscopy. To visualize actin mRNA in cortical neurons (4 d in culture) with higher resolution than conventional epifluorescence microscopy, we took a series of optical sections (100 or 250 nm) from each cell and further processed them by using deconvolution algorithms and applying a point spread function (Fay et al., 1989). A, Localization of β-actin mRNA within a single optical section (250 nm) of a cell body and minor processes (unprocessed image). The fluorescence intensity within the neurite shaft was low. A concentration of β-actin mRNA was observed within the growth cone. B, The same image after restoration. A punctate distribution was observed throughout most of the processes. Note the concentration of β-actin mRNA within one of the growth cones (arrow). C,D) Localization of β-actin mRNA within an axon and its growth cone. The cell body is at the top of the image, and the axon extends downward, terminating in an elaborate growth cone. Note the concentration of β-actin mRNA granules within the central domain (arrow) and few granules within peripheral regions (curved arrow). Scale bar, 10 μm.