In the popupmenu how to show the serial number of the choice?

I have a list (string cell array) where I store the description of an object. When I present it in the popupmenu it would be nice to have the serial number of the choice as well. I do not want to incorporate serials into the list because it is possible to change the order of the objects, so before I put the list on the popupmenu I would like to put the actual serial numbers there.

Please help, how to do this, to add simply a number to a string cell array. Some elements of the array might also be empty, therefore in AA=string(list) command I get "Error using string Conversion from cell failed. Element 19 must be convertible to a string scalar."

Here element 19 is empty.

Thanks.