Scientists have identified the principles of embryonic development of branched dendritic trees of neurons of Drosophila: the growth of major primary process is strictly defined and is perpendicular to the secondary dendrites elongate stochasticity increase, then decrease and change direction. The key for the formation of the structure of the dendritic tree were internal regulation: coming into contact, the processes of “start” and begin to decrease, but are unable to contract on the nearest branch. A Preprint of the article is available on the portal bioRxiv.
Dendritic trees — system of receiving signals processes of neurons — are very different different types of nerve cells. The bipolar neurons, for example, from the body in opposite directions moving away two bundles of dendrites, the stellate appendages diverge in all directions, and Purkinje cells are all large tree is in the same plane.
On the formation, growth and branching of dendrites is affected by many intracellular factors, signals of other cells and the activity of the neurons themselves. However, we still unknown, what determines the geometry of the dendritic tree, whether it is the formation of a stochastic process probabilistic or strictly deterministic. In other words, we do not know whether the growth of each branch, environmental factors, or laid down the basic principles of tree growth.
French scientists from the University of AIX-Marseille under the leadership of Thomas Lekai (Thomas Lecuit) followed by the formation of the dendritic tree of neurons in fruit flies Drosophila melanogaster during embryonic development. Have nerve cells that are selected for study, there are two main dendritic trunk that extend from the neuron’s body (large and small), and the secondary branches branch off from the perpendicular to them — the result is a structure resembling a bottle brush for the bottles.
For a start, the researchers assessed the structure of the dendritic tree on the four stages of larval development, and then visualized the formation of a system of processes throughout embryogenesis. It turned out that the larvae neurons grow in proportion to the whole body, but their structure does not change: the number of primary, secondary and tertiary processes, their relative length and position was laid during embryonic development.
The growth of the tree took place as follows: first appeared and grew larger primary process, in an hour it began to appear perpendicular to the dynamic processes that uitgevers, then again decreased, and on them many small tertiary processes. After a few hours secondary dendrites stabilized, the number decreased and tertiary structure ceased to change.