Alignment analysis of collagen gels at 3 mg/ml and comparison with 2 mg/ml.

<p>Images of acellular (a) and spheroid embedded (b) 3 mg/ml collagen gels were analyzed using the orientation detection algorithm. The scale bars are 20 <i>μm</i>. AI values were determined from the histograms of acellular collagen gels (c), AI = 0.086, and spheroid embedded collagen gels (d), AI = 0.357. (e) Among all the experimental collagen gel images, the AIs of acellular collagen gels are 0.096±0.027 at 2 mg/ml, 0.115±0.031 at 3 mg/ml, and 0.127±0.025 at 4 mg/ml. The AIs of 2mg/ml and 3mg/ml spheroid embedded collagen gel are 0.386±0.027 and 0.346±0.079. The error bars are the standard deviation calculated among all images under the same experimental conditions. They are all significantly different with each other by the Welch two sample t-test.