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Title: Quantitative studies on the positioning of cells in aggregates
Author: Tickle, Cheryll
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1970
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"Sorting out", that is the grouping of cells according to typo and the positioning of cell types relative to the inside and outside in aggregates has boon investigated in aggregates formed from mixtures of disaggregated 5 day embryonic chick heart and limb bud cells, The cell types were recognized in aggregates by radioactive labelling. Two quantitative tests for segregation of cells according to typo have been used, one attempting to relate to the two cell typos used and incorporating corrections for percentage labelling of labelled cell suspensions. In some cases the positioning of cell types within aggregates has been analysed quantitatively. Data from mixed aggregates of "labelled" and "unlabelled" limb bud cells provided a crucial control. Each experiment has been carried out using reciprocally labelled cell suspensions. The time course of "sorting out" and the effects of three disaggregation procedures on this process have been examined. A marked degree of segregation of cell types in aggregates formed after 2 and 4 hours reaggregation in couette viscometers was found. Tentative evidence was obtained that heart cells may be positioned internally in those aggregates formed from RDTA disaggregated cells. When the cells are reaggregated in reciprocating shakers for 42 hours the grouping of cells in resultant aggregates was found to be less segregated than in the aggregates/aggregates formed after 2 and 4 hours reaggregation. In aggregates formed after 48 hours reaggregation, in gyratory shakers, of cells disaggregated with EDTA, the cells show the same degree of segregation as in aggregates formed from cells similarly disaggregated after 2 hours reaggregation and heart cells were positioned externally. Cells disaggregated by the three procedures investigated show different degrees of segregation in aggregates formed after 2, 4 and 42 hours reaggregation. The results have been discussed in relation to theories explaining "sorting out".
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available