BEHAVIOR OF ISOLATED CELLS 



215 



Holtfreter, 1946: Jour. Morphology. Ti-.Tl . 



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MIGRATION *HD ADHESION 



10 ATTRACTION WITHOUT ADHESION 



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Holtfreter, 1947: Jour. Morphology. 80:57. 



Isolated amphibian gastrula cell. 



Ectoplasmic movements in isolated Embryonic Cell. 



Rotating movements in the absence of (Fig. 3), and in the presence of endoplasmic sol-gel fonnation (Fig. 4). 



Fission of a cell into unequal halves. 



Unfertilized frog egg budding off spherical fragments. 



Migrating vermiform cells, isolated from the medullary plate, failing to aggregate. 



Cells from the medullary plate becoming adhesive to each other while changing from a cylindrical into a spherical 



shape, the intervals between each picture being about 5 minutes. 



Successive phases of kinetic relations between a sessile and a migrating neuroblast. 



Three ectoplasmic cell fragments exhibiting reciprocal attraction, but no adhesion. 



Ectodermal cells in the process of aggregating, the whole process taking about 20 minutes. 



Aggregations comprising various numbers of cells, some of which are at the same time spreading on glass. 



Spreading embryonic cell containing 2 particles of carbon. 



Cylindrical cell having ingested a drop of pwraffin oil. 



Neuroblast attempting but failing to incorporate a droplet of paraffin oil. 



Neuroblasts leaving an embryo which has been exposed to a hypertonic salt solution. 



