Table 1

Quantitation of pericyte elements in association with microvessels in E16.5 mouse brains. Microvessels with whole lumina that were encountered in EM sections were counted and classified into the following categories: (a) naked endothelial tubes; (b) pericyte processes present (figures might represent an overestimation because abluminal folds and overlappings of endothelial cells could be misinterpreted as pericyte processes); (c) microvessels with pericytes sectioned through the nucleus; (d) lumina are part of a clear sprout (because of the presence of a highly convoluted microvessel cell surface in sprouts, the classification into endothelial or pericytic elements is difficult and was avoided); and (e) not possible to classify in other categories, for example, because of oblique sectioning. The total number of PDGF-B −/− microvessels analyzed was 173. The total number of PDGF-B +/+ or +/− microvessels analyzed was 213.

Embryos (genotype)Microvessel category
abcde
1 (−/−)506040
2 (−/−)470041
3 (−/−)461022
Sum15370103
4 (+/+ or +/−)2421150
5 (+/+ or +/−)2351445
6 (+/+ or +/−)421620
7 (+/+ or +/−)537972
Sum1313540187