Hi Olga, I believe the problem originally mentioned in this thread is that ZBrush decides to automatically "unweld" the points in some particular areas like the pole of a sphere.

Look for an option in ZBrush that may be called something like "weld" or "merge vertices". It may be an import option or a specific command that you can run.

You need to get the polygons to share a single point instead of each one having their own point. When they share the same point between them they will be connected to one another more strongly and will not separate then.

Normally this is achieved by turning on the "Weld vertices along edges" option that can be turned on in the Meshing options dialog box when you save out from MoI (push the little arrow in the lower left corner to expand the dialog to see it). But in this particular case ZBrush decides to "unweld" the points at the pole itself so you will need to use some kind of weld function inside of ZBrush to combine those stacked up points into 1 single point.


ZBrush also will tend to like much more evenly sized polygons, there is some information on how to create a mesh like that here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=1549.4

- Michael