Table 2.

Gene expression data, R side Xnr1-engrafted embryos

A) Mid-trunk placement
Stage	Gene	n embryos (#expts. pooled)	n (%)L-sided	n (%)R-sided	n (%)bilateral	% Anterior truncation (%truncated plus suppressed)	Figure
St. 23	Xnr1	12 (2)	2 (17)	-	10 (83)	-	Fig. 3
St. 24/25	Xnr1	21 (3)	-	-	21 (100)	90 (47)	Fig. 3
St. 26	Xnr1	9 (1)	-	9 (100)*	-	-	Fig. 3
St. 24/25	Xlefty	16 (3)	2 (12)	-	14 (88)†	100 (0)	Fig. 4
St. 28	XPitx2	13 (2)	2 (15)	1 (8)	10 (77)	60 (0)	Fig. 4
B) Posterior placement
Stage	Gene	n embryos (#expts. pooled)	n (%)L-sided	n (%)R-sided	n (%)bilateral*	Figure
St. 24/25	Xnr1	10 (1)	2 (20)	-	8 (80)	Fig. 5
St. 24/25	Xlefty	11 (2)	1 (9)	2 (18)	8 (73)	Supp. Fig. 4
St. 28	XPitx2	5 (1)	-	-	5 (100)	Supp. Fig. 4
C) Mid-trunk placement plus midline extirpation
Stage	Gene	n embryos (#expts. pooled)	n (%)L-sided	n (%)R-sided	n (%)bilateral*	Figure
St. 24/25	Xnr1	6 (1)	-	-	6 (100)	Fig. 5
St. 24/25	Xlefty	13 (2)	-	1 (8)	12 (92)	Supp. Fig. 6
St. 28	XPitx2	6 (1)	-	-	6 (100)	Supp. Fig. 6

R-side βgal-engrafted controls showed normal L-side expression and anteriorward progression of Xnr1 (at St.24/25), Xlefty and XPitx2, respectively: n=14/14; n=12/12; n=9/9.

^*All R-side mid-trunk Xnr1-engrafted embryos at stage 26 showed perdurant Xnr1 expression in R LPM whereas endogenous L-sided expression had disappeared.

^†Ectopic midline and R side dorsal endoderm expression was also observed in 100% of engrafted embryos showing bilateral Xlefty expression (see text).

^*Posterior placement of R side Xnr1-graft resulted in mirror image L & R expression. Of embryos with bilateral expression, no suppression of anterior progression or intensity of L-sided expression was observed compared to the graft-induced R side expression.

^*Removal of midline tissues in mid-trunk R side Xnr1-engrafted embryos led to mirror image L & R expression.