| Popis: |
The morphology of a neuron is key to its function, but the principles that govern neuronal morphogenesis are not clear. To investigate these principles, we used the larval class IV sensory neuron in Drosophila as a model cell. Class IV neurons have highly branched dendritic morphology. Our specific question is whether this branching morphology arises from purely random processes or whether there exist non-random constraints on morphological parameters such as segment lengths and branching angles.To measure the statistical characteristics of the dendritic arbors, we imaged class IV neurons by confocal microscopy and analyzed their skeletons using Fiji and Matlab. First, we found that the lengths of dendritic segments, both terminal and non-terminal, followed exponential distributions. Given that the lengths of the dendritic segments are defined by consecutive branch points, this observation suggests that branching events follow a spatial Poisson process. Second, we found that the angles between two daughter segments follow a normal distribution with a mean of 96 degrees and a standard deviation of 31 degrees (n = 465). Because the mean differs from 180 degrees, we conclude that the branching angles are not uniformly distributed. These properties, namely the distributions of segment lengths and angles, were observed throughout morphogenesis.Our results indicate that there are morphological properties of class IV neurons which are not determined by purely random processes. |
