Figure 10.

Overview of Position-Dependent and Position-Independent Events.

(A) and (B) The placement of the first precursor cell, the MMC, is random.

(C) The placement of asymmetric divisions of separated MMCs appears to be random.

(D) and (E) Divisions of MMCs in contact are randomly oriented and can produce meristemoids in contact.

(F) The orientation of asymmetric divisions in neighbor cells depends upon the position of the stoma or precursor.

(G) Asymmetric divisions of adjacent meristemoids can be oriented and thus space stomata.

(H) Cells next to two stomata or precursors (asterisks) follow a pavement cell fate, but this does not directly create the one-celled spacing.

(I) Adjacent meristemoids can become pavement cells (asterisk) and thus space stomata.

MMCs are shown as stippled regions in (A) and (B). Meristemoids are dark gray.