Fig. 4. Quantitative analysis. (A) Quantitative analysis of typical neural crest migratory streams (n=8) shows that different cell shapes (bipolar versus hairy) are distributed in different positions along the stream. The graph plots the percent of hairy versus bipolar cells at the front (distal), middle and back (proximal) of typical neural crest cell streams as a percentage of the total number of cells in the stream. The majority of bipolar cells are located in the middle of the migratory stream, while there are almost three times as many hairy cells versus bipolar cells at the front of the stream. At the back portion of a stream, the percentage of hairy and bipolar cells are nearly equal. (B) Further quantitative analysis of the directional distribution and length of the filopodia on hairy versus bipolar cells is shown in the second set of graphs. A sample of hairy and bipolar cells (n=16) within typical migratory streams were selected and the filopodia lengths and spatial distributions were measured. Bipolar cells have the feature of having few long filopodia that typically extend into the first two quadrants, forward (toward the branchial arch) and trailing (toward the neural tube). In comparison, hairy cells have a large number of filopodia extending from nearly all aspects of the cell's circumference, seen in thick lines in all four quadrants. The filopodia are slightly longer in the directions toward the branchial arches and the neural tube. (C) A typical migrating neural crest cell was analyzed for the dynamic cell shape changes. The quantitative analysis of the area of a trailing cell, plotted as a function of time, reveals that the area of the cell does not increase monotonically in the direction of motion, but oscillates slightly.