DEVELOPMENT OF SURFACE PATTERN DURING DIVISION IN PARAMECIUM .3. STUDY OF STOMATOGENESIS IN THE WILD-TYPE USING ANTITUBULIN ANTIBODIES AND CONFOCAL MICROSCOPY

Stomatogenesis, during the vegetative division of Paramecium, is a com plex morphogenetic process involving massive proliferation of basal bo dies and their progressive patterning to generate a new oral apparatus in the immediate vicinity of the old one. This new oral apparatus wil l be inherited by the posterior daughter cell while the old one remain s in the anterior daughter cell. We have carried out a detailed descri ption of the whole process, using new antibodies and confocal microsco py, allowing visualization of all basal bodies and a number of other c ytoskeletal elements, thus completing our previous description of morp hogenesis. The following inferences could be made: 1) The new oral str uctures are exclusively formed from the anarchic field by a two step w ave of basal body duplication. These two steps strictly parallel, slig htly in advance, those we have previously detailed at the level of the ''somatic'' cortex, suggesting ()) that a common set of biochemical cascades is involved, (*)) that the OA may be triggering these cascad es. 2) The initial proliferation of basal bodies occurs in the immedia te vicinity of the parental ''paroral kinety'' which itself remains in variant and appears to dictate the progressive patterning of the oral anlage (as can be inferred from the staining intensity, distance and a lignment of the basal bodies of the anarchic field with respect to the paroral kinety). This suggests that the concept of cytotaxis or struc tural guidance can be extended to the genesis of an elaborate set of b asal bodies. 3) The number of basal bodies within the anarchic field i s determined during this formation of the new oral apparatus. Thus, th e size and possibly part of the pattern of the new OA is determined in one generation, with storage of morphogenetic potentialities used in the next generation. In this process, a slight cortical rotation aroun d the cell axis is effected at each division. 4) The whole morphogenet ic assemblage up to the level of the whole cell displays an overall le ft-right asymmetry which is progressively built up upon the basic asym metry of the basal body.