In situ analysis of expression of meristem and early primordium genes in wild type and the quadruple aux1 lax mutant. Central sections of a series of longitudinal sections through wild-type and quad vegetative meristems. (A) CLV3 in wild type. (B,C) CLV3 in quad. (D) STM in wild type. (E,F) STM in quad. (G) ANT in wild type. (H,I) ANT in quad. (J) MP in wild type. (K,L) MP in quad. Black arrows indicate sites of STM down-regulation in incipient or bulging primordia. Black arrowheads indicate lack of STM expression in the outer ZND. Blue arrows indicate sites of ANT up-regulation in incipient or bulging primordia. Blue arrowheads indicate lack of ANT expression in the outer ZND. Gray arrows indicate MP expression in the peripheral zone of the meristem. (A,B,D,G,J) 33–39 DAG, (C,E,F,H,I,K,L) 55–65 DAG. Bars, 50 μm.