Abstract
The problem of the sexual differentiation of the neoblasts of planarians is approached on the basis of karyological evidence assembled by the author and by his collaborators. In the polyploid and pseudogamic biotypes of Dugesia benazzii, D. lugubris and Polycelis nigra, the transformation of the neoblasts into oogonia or spermatogonia is accompanied by variations in the chromosome set. These variations may be considered to be dependent upon the gradient of sexuality — that is, of the territorial influences that determine the evolution in a female or a male direction. Significant evidence is also inferred from the chromosome cycle of hybrids between amphigonic diploid biotypes and polyploid biotypes. A new direction of research, based on the comparison between anterior and posterior regenerated segments of experimental polyploids with variable chromosome sets aims at establishing possible regional differences in the set of the neoblasts.
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Dedicated to Prof. Dr. J. Seiler on the occasion of his eightieth birthday.
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Benazzi, M. Considerations on the neoblasts of planarians on the basis of certain karyological evidence. Chromosoma 19, 14–27 (1966). https://doi.org/10.1007/BF00332791
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DOI: https://doi.org/10.1007/BF00332791