Computer-aided 3-D reconstruction of serially sectioned mouse embryos: its use in integrating anatomical organization.

This paper reviews recent work on a project that uses a computer-aided approach for making 3-D reconstructions of serially sectioned mouse embryos (the digital mouse). The captured images are aligned using a warping program so that almost perfect alignment of adjacent sections is achieved with minimal deformation. The sections that are viewed on the computer screen are in fact computer-generated grey-level images with a resolution of about 10 microm. The reconstructed embryo may then be resectioned in any plane to simulate as near as possible an exact match on the computer screen to the viewer's own material. Individual anatomical domains may then be painted in different colors, and these domains may be selected by querying the textual database containing anatomical and other information. Further, it is now possible to generate 3-D images of individual anatomically-discrete components or related sets of components of a particular system in isolation from the rest of the embryo, or, if required, against a 'ghost-like' image of the intact embryo, or specific parts of an embryo. In the article, examples are given of the use of the system in interpreting the vascular, gut and paraxial mesoderm systems, while both the advantages and disadvantages of this approach are also discussed. The eventual aim will be to provide 3-D reconstructions of mouse embryos from fertilization up to 14 days postcoitum of development. When completed, this project will allow the accurate spatial mapping of gene-expression and cell lineage data onto the digital Atlas of normal mouse embryonic development.