Figure 10
Lack of junctional complexes and collagen deposition revealed by electron microscopy analysis of yolk sac tissues. Yolk sac tissues from wild-type (A, B, C) and Tie2Cre+/-Srff/f(D, E, F) embryos were subjected to transmission electron microscopy to assess ultrastructural detail. Desmosomal-type junctional complexes are observed in wild-type tissue (B arrowheads) but not in mutant tissue (E). Intralaminar collagen deposition occurs normally between endodermal and mesodermal cell layers in wild-type (A, C) but not mutant (D, F) tissues. Arrowheads in C denote longitudinal and cross-sectional views of individual collagen fibrils. Boxes in A and D correspond to images in B and E, respectively; asterisks in A and D correspond to images in C and F, respectively; scale bars: A, D = 1 μm; B, C, E, F = 0.2 μm.