A model for chromosome movement based on lateral interaction of spindle microtubules.

Quantitative morphological studies of meiotic spindles in the crane fly Pales ferruginea (Fuge, 1980, 1984, 1985) were the basis for the development of a model explaining anaphase chromosome transport in higher eukaryotes. Two main features of chromosome fibres were important for the model: (1) the existence of microtubules oriented obliquely with respect to kinetochore microtubules, and (2) a higher degree of disorder in fibres exerting a pulling force. It is postulated that microtubules of the same polarity being inclined to each other at a certain angle are able to slide past each other by means of mechano-chemically active side-arms working in alternate succession. Sliding is suggested to lead to a displacement of microtubules and chromosomes in direction towards the poles. Furthermore, it is suggested that the chromosome fibre in anaphase becomes progressively disintegrated by fragmentation and disassembly of microtubules. Fragmentation may be induced by bending stress within the dynamic system.