Fig. 6. GRPCWM in the protoxylem of other seed plants. (A-I) Confocal 3D reconstruction of the protoxylem of different species after staining with bean GRP1.8 antibodies. (J) Differential interference contrast, Coomassie-Blue staining. (A) Arabidopsis thaliana hypocotyl. The GRP network is restricted to the protoxylem, as in soybean. The ring-shaped SW (arrow) is tilted, probably owing to the collapse of the PX. Arrowheads, helical SW; m, metaxylem. (B) Nicotiana tabacum hypocotyl. Two ring-shaped SW are interconnected by a helical SW. (C) Leucojum vernum, floral axis. SW in the form of squares, interconnected by four filaments of GRPCWM. (D) Galanthus nivalis floral axis. GRPCWM is associated with ring-shaped SW. Arrowheads indicate the position of missing ring-shaped SW. The GRPCWM between two adjacent PX is indicated by arrows. One of the partners was removed by the isolation procedure. (E) G. nivalis floral axis. GRPCWM (arrow) interconnects the ring-shaped SW of two PX. Side view of a situation similar to (D). (F) G. nivalis floral axis. Rabbit serum control. As in soybean, the GRPCWM is faintly stained with ethidium bromide. (G) Pinus sylvestris cotyledon. Thin filaments of GRPCWM interconnect the SW. (H) Picea abies hypocotyl. Anastomosing SW are interconnected by GRPCWM. (I) P. abies hypocotyl. Rabbit serum control. As shown for other species the GRPCWM is faintly stained with ethidium bromide. (J) P. abies hypocotyl. Differential interference contrast microscopy. Arrows, filaments stained with Coomassie Blue. Bars, 10 µm.