Motility, linear arrangement and cell-to-cell contact of myogenic cells prior to fusion.

Time-lapse cinematography elucidates the genesis of a uniform and approximately linearly arranged myogenic cell aggregate, stemming from two larger cell groups. The ultimate aggregate is created by continuous movement of one cell group toward the other. Following this motion, the angle between the cell groups is reduced as they approach each other. Different patterns of cell motility can be recognized. Some cells move in a preferred direction in relation to the aggregate as a whole, whereas others alter their direction of movement. The myogenic cells are aligned end-to-end and side-by-side. The latter is often accomplished in the following manner: two cells in end-to-end contact form as crescent-shaped free space with their polar extensions; a neighboring spindle-shaped cell then settles in this space. An arrangement of cells such that their greatest cytoplasmic widths lie at the same level can also be seen. During the recording period, two cells in one of the groups were replicating. One of them realized karyo- and cytokinesis in approximately 80 min. The daughter cells moved apart in opposite directions, but never lost contact to the aggregate. This observation shows that contact between presumptive myoblasts and myoblasts is established.