Survival of purified motor neurones in vitro: Effects of skeletal muscle-conditioned medium

Spinal motor neurones in the adult mouse were labelled retrogradely with both True Blue and horseradish peroxidase (HRP). Using the cell sorter, motor neurones were separated on the basis of cell size and the intensity of True Blue fluorescence. Cultures of the sorted cells were then prepared and the motor neurones were identified by their HRP labelling. There was found to be a 4.8-fold increase in motor neurones over the unsorted population such that 40% of the cells present in culture was labelled. Medium conditioned over skeletal muscle was shown to enhance the survival of motor neurones in these cultures.