Colony architecture and topology of different cell types. (A) Vertical transverse cross sections of BR-F colonies stained with ConA-AF (ConA) and BR-F–Hmg1p-GFP (Hmg) colonies. Vertical white lines mark the borders of three individual colonies. (B) Typical morphology of cells in roots and the upper colony region (magnified regions are marked in A). (C) Cell morphology in BR-F–Hmg1p-GFP colonies. Areas with stationary (red bar), dividing (green bar), and young nondividing (blue bar) cells are shown. Arrows indicate examples of dividing (white) and stationary (red) cells (magnified regions are marked in A). (D) Distribution of dividing cells in root tips of BR-F–cdc3^ts colonies. Examples of cells reaching a terminal phenotype (Fig. 2 A) are marked by arrows. (E) Velcrolike interconnection (marked by arrows) between cells in the upper central region of 3-d-old colonies visualized by EM (more in Fig. S1). (F) Diagrammatic illustrations of the cell topology in the course of colony development (based on BR-F–Hmg1p-GFP and BR-F–cdc3^ts data; also see Fig. 2). Regions with dividing (green), early stationary (yellow), stationary (red), and younger with no apparent division activity (blue) cells are shown. Two (A, 60 h and 3 d) or three (A, 7- and 3-d merged colonies) individual images spanning the width of the colony were acquired and assembled after acquisition to generate the composite image shown. Details in B2 and C1 were obtained by composing two images of neighboring fields of view.