A primary neural tube culture assay was used to study the early stages of melanoblast specification, proliferation, and migration. This assay was used to study the roles of different cell signalling pathways known to affect melanoblast development <i>in vivo</i>. KITL significantly affected both the proportion of crest cells that were melanoblasts and the distance they migrated, while EDN3 only affected melanoblast numbers. HGF increased the migration distance of melanoblasts in culture, while MSH affected neither melanoblast migration nor numbers. Studies of adult chimaeras derived from embryos carrying different coat colour markers have suggested that total melanoblast population is derived from a small number of progenitors, each generating a discrete unilateral transverse band of colour with minimal mixing between clones. In this study, two complementary approaches were used to assess the behaviour of labelled clones during development. Firstly, aggregation chimaeras were made between <i>Dct-LacZ</i> and non-transgenic embryos. The <i>Dct</i> promoter drives expression from E10 in melanoblasts and in cells of the telencephalon. Resultant patterns of labelled melanoblasts were studied during mid-gestation. Secondly, transgenic mice were generated that carry a modified <i>LaacZ </i>reporter construct containing a 300bp duplication (<i>LaacZ</i>) under the control of the <i>Dct</i> promoter. The <i>LaacZ</i> transgene is normally inactive, but it reverts to wild type <i>LacZ</i> at low frequency, labelling a cell and all its progeny apparently at random. Together, chimaeric and mosaic embryos suggested the melanoblast population is derived from a large number of progenitors, a pool of melanoblasts may reside in the cervical region, and melanoblasts within a clone show considerable longitudinal migration, suggesting there is significant axial mixing between clones. Interestingly, radially arrayed labelled clones were also generated in the telencephalon in <i>Dct-LaacZ</i> embryos.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:663778 |
| Date | January 2002 |
| Creators | Wilkie, Alison Louise |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/23260 |
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