Effects of gel thickness and depth of needle insertion on the measured area of fiber alignment (average +/- std. error). (A) 2 mm-thick and 4 mm-thick gels; (B) 6 mm-thick gels. For the same depth of insertion, thin gels demonstrated more alignment than thick gels. For both 4 mm- and 6 mm-thick gels, the alignment area increased as depth of insertion increased.