Axis.MinorTickMark (PowerPoint)
Returns or sets the type of minor tick mark for the specified axis. Possible return values are xlTickMarkCross - Crosses the axis, xlTickMarkInside - Inside the axis, xlTickMarkNone - No mark, xlTickMarkOutside - Outside the axis.
MinorTickMark can be one of the following xlTickMark constants:
ActivePresentation.Slides(1).Shapes(1).Chart.Axes(1).MinorTickMark = xlTickMarkCross