| Abstract: | The aberrant, a morphological mutant of Hydra attenuata, has altered patterns of the development and distribution of nematocytes. The number of nematoblasts and nematocytes is higher in the aberrant than in the normal. Stenotele differentiation is incomplete and the numbers of desmonemes and holotrichous isohrizas mounted on the body column are much higher than normal. Because nematocytes arise by differentiation from the interstitial cells, epithelial cell/interstitial cell chimeras between the aberrant and normal strains were made to determine whether the lesion giving rise to the alterations in the mutant was due to the epithelial cells or a cell type in the nematocyte lineage. Only the chimera in which both cell types were derived from the aberrant exhibited the altered nematocyte development. If the chimera contained a normal cell type, either epithelial cell or interstitial cell, nematocyte development was normal. Thus, both epithelial cells and cells of the nematocyte lineage are involved in the control of nematocyte development. A defect in one of the lineages can be compensated for by the other cell type. |
