Fig. 3. Migration of mesoderm into T^C/T^C allantoises from the primitive streak is normal, but proliferation, cell number and allantoic length are reduced. (A) Whole-mount images of the allantois (al) and primitive streak (asterisk) at the time of (a,d) and 12 hours after (b,c,e,f) injection of DiI (red) into the primitive streak of +/+ (a-c) and T^C/T^C (d-f) EHF conceptuses. (a,b,d,e) Live images of the posterior end (up) through the yolk sac; (c,f) live images of the dorsal allantoic surfaces after the yolk sac was peeled away. The green line in a,b,d,e represents the boundary between the allantois and primitive streak; the yellow line in c,f outlines the extent of the allantois. Scale bar in d: 500 µm for a-e, 250 µm for f. al, allantois; ch, chorion. (B) Mitotic index (MI) calculated for the allantois (a) and primitive streak (b) for +/+, T^C/+ and T^C/T^C genotypes over the 6-hour window during which allantoic length and cell number were reduced in T^C/T^C. Error bars represent s.e.m.; P-values for each mutant genotype with respect to +/+ are reported below each data point. (C) Bar graph of allantoic nuclei counts in +/+, T^C/+ and T^C/T^C genotypes for the interval LB to 1-s. (D) Bar graph of allantoic lengths (in µm) in +/+, T^C/+ and T^C/T^C genotypes for the interval EHF to 1-s. In C and D, error bars represent the s.e.m.; P-values for the mutant genotypes with respect to +/+ are reported above each bar.