Fig. 7. Loss of Gliolectin expression affects commissure and longitudinal formation. Phenotypes associated with loss of Gliolectin indicate that this carbohydrate binding protein functions to capture axons at the surface of the midline glial cells (shown in gray) in which it is expressed. For longitudinal axons (shown in blue), capture facilitates the transmission of signals that keep them from crossing the midline (Robo, Slit). In the absence of Gliolectin, longitudinal axon extension is delayed. For commissural axons (shown in red), capture ensures the transmission of signals that allow midline crossing (Commissureless, Netrins) and contributes to the formation of a favorable growth substrate. In the absence of Gliolectin, early commissural axons grow upon other axons rather than in close association with the midline glia.