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Das radialpolare Differenzierungsmuster bei Trichoplax adhaerens F. E. Schulze (Placozoa) / The Radial Polar Pattern of Differentiation in Trichoplax adhaerens F. E. Schulze (Placozoa)

Schwartz, Viktor
Zeitschrift für Naturforschung 2014 v.39 no.7-8 pp. 818-832
Trichoplax, models, provenance, staining
In contrast with the outmost uniform aspect of Trichoplax there is a clear cut differentiation between marginal and central cell territories. Dissection and transplantation as well as vital staining show that the marginal material is restricted to a seam approximately 20 μm in width, surrounding the much larger mass of central cells. Isolated marginal or central cell material can not regenerate a complete individual and is therefore doomed to die. Regeneration requires the presence of both components because the cells propagate true to type only, meeting the Ruthmann model (A Ruthmann, Cytobiol. 15, 58 (1977)). There is no redifferentiation between marginal and central cells. Marginal pieces transplanted into the central area produce an inverted inner edge, surrounding an open hole. Dissection or transplantation borne frag­ments containing sufficient cells of both marginal and central provenience reassort their cells to the normal relative position. Unbalanced compositions of fragments may be regulated by detachment of surplus material or (in the case of marginal surplus) also by fission, even in very small individuals. This way fission is involved in the regulation of the quantitative relation between these two kinds of cells. A monstrous modification of the shape and physiologic properties demonstrates a disturbance of these regulations. The marginal versus central differentiation manifests a radial polarity, till now unknown as to the relation to the histologically discerned cell types.