Text and images
© Jeremy Cook 1997–2008

		Structure and content : 2 Structural features and organization  The organizational core of ‘The Embryonic Disk’ is its contents page, which is linked to every main page and always available as a safe harbour for navigators. The pedagogical core of the resource, however, is an illustrated timetable grid of 28 days, organized into rows representing the first four weeks of development. Each element of the grid is a captioned image that refers to the day's most salient event, and the image is hotlinked to a screen page where the theme is developed. A similar grid is used to represent the relationships between the body systems of the adult and four key developmental topics that span more than one system and extend through the second month. The elements of this schematic grid (see Home page) are also hotlinked to the relevant screen pages. The simple introductory tutorial, 'Egg to Embryo’, employs a straight-through narrative structure, without hypertext links. It is particularly useful for paramedical students who lack background in this area. In all other sections of the resource, material that we consider core material for medics and paramedics is visible on each page as it appears, and a wide variety of supplementary material (including microscopic sections) can then be popped up as required, mostly over the same page so that there is no risk of getting lost in a maze of navigation links. Supplementary material includes: Additional images and image sequences: icons activating pop-up viewers for relevant full-colour photographs or animations, some in viewers and others filling the entire page area. Notes and commentaries: material of greater complexity, breadth or interest, presented in almost 400 pop-up commentaries, each in a ‘More’ box, hotlinked to a marker in the core text. Literature references: pop-up references to background literature and further reading on points of contention or of current research interest, hotlinked from ‘More’ boxes on those topics.