Figure 3. Basal lamina deposition in tumor blood vessels.

(A) To evaluate basal lamina assembly associated with blood vessels, sections of 7-day tumors were double-stained for CD31 (red) and collagen IV (green). Bar = 100 μm. (B) Data in panel B are derived from 3 independent tumors for each genotype, sampling 4 fields from 3 sections in each tumor. Both day 5 and day 7 tumors were analyzed. Confocal z-stacks of images were processed by image analysis to quantify the extent to which collagen IV labeling overlapped with CD31 labeling. Basal lamina deposition is reduced in the NG2 null mouse at both time points. * P< 0.002. (C) Association of collagen VI with 7-day tumor blood vessels was evaluated in wild type (wt), NG2 null (NG2 ko), and collagen VI null (coll VI ko) mice by double-staining for CD31 (red) and collagen VI (green). Bar = 100 μm. (D) Data in panel D are derived from 3 tumors for each genotype, sampling 4 fields from 3 sections in each tumor. Image analysis of z-stacks of confocal images allowed determination of the percentage of CD31 pixels covered by collagen VI pixels. * P<0.03. ND, not detectable. (E) Assembly of collagen IV-positive basal lamina was compared in tumor vessels in wild type, NG2 null, and collagen VI null mice. ** P< 0.007 *** P< 0.002