Microtubules (MTs) are the most prominent structural elements of the spindle apparatus. Consequently they are generally thought to a play a role in the processes of spindle elongation and the autonomous chromosome movements towards the spindle poles in anaphase. Recent electron microscopic studies have confirmed that dynamic changes in MT arrangement and distribution occur during chromosome movement. Furthermore, the anaphase movement seems to be accompanied by a decrease of the overall spindle MT content and possibly by MT shortening. The main purpose of this article is to review and to discuss recent morphological observations on spindle MT arrangement and the role of the kinetochores, since a general morphological spindle concept would be a prerequisite for the understanding of spindle mechanism. Already existing hypothetical spindle models are shortly discussed in this context.