The Edinburgh Mouse Atlas: using the CD.

This paper provides a simple introduction to the reconstructions and data-handling tools stored on the Edinburgh Mouse Atlas CD, together with some of the ways in which the viewers and software can be used to understand mouse development and analyse data. The key aspect of the Mouse Atlas is that the underlying models are a complete representation of the histology, which has not been constrained to a particular interpretation. This means, for example, that the current anatomy domains can be further subdivided as required to any resolution up to the resolution of the models (2-7 microm). In the CD of the early embryos described here, virtually all tissues that can be usefully distinguished either by the histology or morphologically have been delineated.

A three-dimensional model of the mouse at embryonic day 9.

This paper describes a digital, three-dimensional model of the mouse embryo at E9. The model was made by reconstruction from images of serial histological sections digitally warped to remove distortions and has a resolution of approximately 9 microns. The model can be digitally resectioned in any plane to provide images which resemble conventional histological sections. The main tissues have been identified and delineated by digital painting so that the anatomical components can be visualized and manipulated in 3-D surface- and volume-rendered views. This provides a three-dimensional definition of anatomy that will provide a useful tool for interpreting and understanding spatial data in mouse embryos. The anatomy of the model is discussed where it provides landmarks for interpretation and navigation or where it is unexpected in light of existing descriptions of the E9 mouse embryo. The complete anatomy is not presented in this paper but will be available on CD-ROM. A detailed description of the technical aspects of the construction of the model is included in an appendix. The model is the first of a series that will form the basis for an atlas/database of mouse development. This reconstruction and its associated anatomy are available in a variety of data formats with some supporting software from http:@genex.hgu.mrc.ac.uk/.

An internet-accessible database of mouse developmental anatomy based on a systematic nomenclature.

This paper reports an internet-accessible database of mouse developmental anatomy (DMDA) that currently holds a hierarchy of the names and synonyms of the tissues in the first 22 Theiler stages of development (E1-E13.5), together with other appropriate information. The purposes of the database are to provide, first, a nomenclature for analyzing normal and mutant mouse anatomy, and second a language for inputting, storing and querying gene-expression and other spatially organized data. DMDA currently contains some 6900 named and staged tissues (e.g. 360 and 1161 tissues in Theiler stage (TS) 14 (E9) and TS22 (E13.5) embryos). DMDA will be extended to include further lineage and other data when it becomes available. The database can be interactively accessed over the internet using either a Java or a non-Java WWW browser at http://genex.hgu.mrc.ac.uk/.

Computer-generated three-dimensional reconstructions of serially sectioned mouse embryos.

We have been involved with a group of computer scientists and anatomists in the development of computer-based methodologies that not only combine the advantages of scanning electron microscopy and conventional histology, but provide the additional dimension of tissue recognition. The latter is achieved by the appropriate labelling of tissues and structures by delineation or 'painting'. Individually segmented anatomically defined tissues can be highlighted in a particular colour and viewed either in isolation or in combination with other appropriately labelled tissues and organs. Tissues can be shown in any orientation either as a transparent overlay on computer-generated histological sections or as 3-D images without the histological background. An additional feature of the system is that computer graphics technology combined with 3-D glasses now also allows the viewer to see the object under analysis in stereo. This facility has been found to be particularly helpful in drawing attention to topological relationships that had not previously been readily noted. As the mouse is now the mammalian model of choice in many areas of developmental research, it is of critical importance that a basic level of skill is available in the research community in the interpretation of serially sectioned material, for example, for the rapidly expanding field in which gene expression studies play a significant role. It is equally important that there is an understanding of the dynamic changes that occur in relation to the differentiation of the various organ systems seen in these early stages of development. What we emphasise here is the additional information that it is possible to gain from the use of this tool which, in our view, could not readily have been gained from the analysis of scanning electron micrographs or by studying conventional serial histological sections of similar stages of mouse embryonic development. The methodology has been developed as part of a large project to prepare a database of mouse developmental anatomy covering all stages from fertilisation to birth in order to allow the accurate spatial mapping of gene expression and cell lineage data onto the digital Atlas of normal mouse development. In this paper we show how this digital anatomical Atlas also represents a valuable teaching aid and research tool in anatomy.

Analysis of fused maxillary incisor dentition in p53-deficient exencephalic mice.

Out of a total of 21 exencephalic p53-deficient embryonic and newborn mice, 6 (28.6%) possessed fused maxillary incisor teeth. On histological analysis of the 5 examples seen on day 19.5 of gestation and newborn mice, 3 varieties were observed: an example of 'simple' fusion, 3 examples of simple fusion each of which contained a 'dens in dente' ('tooth within a tooth'), and a single example in which the fused teeth were associated with a median supernumerary incisor tooth which, while deeply indenting the labial surface of the fused teeth, was in all locations a completely separate unit. 3-D reconstructions of the fused teeth demonstrated that they were all of the fusio subtotalis variety. No gross abnormalities were observed in the other dentition in these mice. It is noted that in mice fused maxillary incisor teeth are relatively commonly associated with both hypervitaminosis A-induced and trypan blue-induced exencephaly. It is believed that the presence of dens in dente within fused maxillary incisor teeth has only once been reported in mice, and the association between fused maxillary incisor teeth and a median supernumerary incisor tooth has not previously been reported in this species.

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.

The mouse atlas and graphical gene-expression database

The large amounts of gene-expression data on mouse development are now too extensive to be stored in any format other than that of a database. Furthermore, as this data is intrinsically graphical and as, in the early developmental stages at least, its boundaries do not map directly to those of anatomical tissues, the natural way to store it is in graphical format. We are therefore constructing a database able to handle such graphical gene-expression data by mapping it onto 3-D reconstructions of mouse embryos whose tissues have been delineated. This article reviews the progress that has been made in this project and describes its two major components, CD-ROMs of the 3-D reconstructions to be held on the user's computer and a gene-expression database that will be maintained at a host site, the two being linked over the internet by a complex Java-based interface for submitting data and querying the database.Copyright 1997 Academic Press Limited Copyright 1997Academic Press Limited

Fluorescence imaging studies for the disposition of daunorubicin liposomes (DaunoXome) within tumor tissue.

Unilamellar liposomes that retain their contents in the systemic circulation can alter the pharmacokinetics of anticancer agents in favorable ways. It has long been recognized that certain liposome compositions may increase the local drug concentration substantially above that achievable with a free drug. We report here that liposomes can alter the in vivo disposition of an entrapped drug not only on a macroscopic but also on a microscopic scale. We show through in vitro studies that intact liposomes composed of distearoylphosphatidylcholine and cholesterol and containing daunorubicin (DaunoXome) are taken up into P1798 tumor cells. These liposomes produce an enhanced cytotoxicity relative to the free drug for incubation times longer than about 8 h. For in vivo studies, we developed and used a noninvasive fluorescence imaging technique to follow the accumulation of liposomal daunorubicin within murine tumors. With this method, we show that the maximum concentration of the available liposomal drug in tumors exceeds that of the free drug, and additionally, liposomal daunorubicin persists at high levels for several days. Total liposome-delivered drug fluorescence from whole tumor extracts peaks at about 8 h. In comparison, the fluorescence intensity of daunorubicin demonstrate persistent high levels of daunorubicin fluorescence within cells and throughout the tumor masses. Free daunorubicin, in contrast, transiently achieves modest levels of fluorescence and rapidly drops to background within a few h. These results indicate distinct mechanisms for the localization of free and liposomal daunorubicin, suggesting that liposmal daunorubicin can provide sustained intracellular levels of the drug within the tumor.