Hi Elisabeth,

The main things that are liable to make an image smaller than the cell it occupies are:
• cell margins; and
• the before/after formatting of the paragraph style they're in.

The menu/ribbon paths in what follows applies to PCs, so the location of items on Mac Word may differ -
For the cell margins, position the cursor in the table then go to TableTools|Layout|Properties > Table > Options and set the margins to 0. If you want to do this for just some cells, use TableTools|Layout|Properties > Cell > Options and set the cell's margins to 0.

For the before/after formatting, use Home|Paragraph > Indents & Spacing and set the before & after values to 0. It might also be an idea to ensure the Left & Right indents are set to 0 while you're there.

To ensure any inserted picture stays with the cell (and automatically re-sizes to fit the available space), insert it as in-line. You can make this the default via File|Options > Advanced > Cut,copy & paste > Insert Picure As > Inline with text. Do note that, if a picture's aspect ratio isn't the same as the cell's, you may still end up with some white space.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]