Fig. 7

Basal protrusions and apical junctions are altered in MZepcam mutants.

(A–L) Transmission electron micrographs of EVL–EVL interphase region of wild-type (A–D,F–K) and MZepcam mutant embryos (E,H–L) at indicated developmental stages. EVL and deep cells are indicated (evl1/2, dc; A–F), basal protrusions are marked by arrowheads (A–D,F,G), apical junctional complexes (AJCs) and their sizes by brackets (G–K), and desmosomes by arrows (G–I,K). (A–D) In wild-type embryos, basal protrusions start to form at early gastrula stages (A). Their lengths increase during gastrulation (B–D), and decrease after gastrulation is completed (F). Lengths in marginal EVL cells (D) are usually higher than in equatorially located EVL cells (C; see also Figure 6). Protrusions are also formed by marginal EVL cells spanning the cell-free zone between the deep cell layers and the yolk syncytial layer (YSL; [10]) (B). In mutants, basal protrusions are much shorter and broader (E). (G–L) AJCs are basally extended in the mutants (H,J,L), compared to wild-type siblings (G,I,K). Panel (M) shows graphical illustration of average lengths of AJCs in wild type and mutant cells at indicated developmental stages. n = 12; standard errors are indicated.