Cytogeometrical determination of ciliary pattern formation in the hypotrich ciliate Stylonychia mytilus. II. Stability and field regulation.

The first regeneration sequence after folding of right fragments of Stylonychia mytilus results in formation of mirror-imaged incomplete doublets illustrating independent determination of polar and lateralaxes. Analysis of the second morphogenetic sequence illustrates that the independent determination of polar and lateral axes is stable through a subsequent cellular reorganization and confirms that cytogeometry participates in determination of ciliary pattern. The morphogenetic inversion of cirral row primordia in this type of fragment is reflected in the structure of the individual cirri. These data not only extend and confirm our earlier study on this type of fragment, but also are consistent with the conclusion derived from data on a different type of mirror-imaged doublet, that global patterning and assembly of ciliature are independently determined.