Optimisation of the experimental technique (BrdU-IddU double-staining) and development of new computational tools have allowed, for the first time, a comprehensive spatio-temporal map of quantitative cell cycle times in the early vertebrate limb. A key question of limb morphogenesis is how genes create the digit pattern. An example of such a gene is Sox9, which is an early marker of chondrogenesis and is, therefore, assumed to follow a pattern similar to early stages of digit patterning. Classical chondrogenic experiments, suggest digital regions are patterned by the intermediate formation of a “digital arch” from which the digits arise in a posterior to anterior order. In contrast, a through analysis of a large number of Sox9 <i>in situs</i> revealed digital regions 1, 2 and 3 branch from a region reminiscent of the tibia (anterior zeugopod) and digital regions 4 and 5 branch from a fibula-like region (posterior zeugopod). Moreover, the Sox9 pattern first arises in digital regions 2, 3 and 4, followed by digital regions 5 and 1. The Sox9 <i>in situ</i> analysis was achieved using newly developed software for the 3D analysis of optical projection tomographic (OPT) images at a very high spatial resolution. These studies have highlighted the importance of integrating practical and computational tools in order to close the gaps in our knowledge and understanding of limb development, and developmental processes as a whole. The computational tools generated for the proliferation studies are valuable in offering a thorough means of analysis of cell cycle times and the new OPT software will be invaluable for the study of both weak and strong gene expression patterns in whole embryos. In the future, the proliferation data and 3D Sox9 <i>in situ</i> data can be incorporated into simulation software, the results of which should shed light upon the interactive effects of different factors upon the process of limb morphogenesis.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:660883 |
| Date | January 2007 |
| Creators | Raja, Sahdia Tabassum |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/30666 |
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