Figure 1. Photoconversion of KikGR-labeled NC cells revealed thin cellular bridges between neighbors and transfer of cytoplasmic material.

Diagram of typical NC cells before (A and G) and after (B and H) photoconversion of KikGR (405nm excitation) in a subregion (box) of an individual cell. Lead and trailing NC cells were identified by position from the neural tube (in vitro, a lead cell was more distal from the neural tube midline; in vivo, a lead cell was more distal from the neural tube midline). (B) Cellular bridges between neighboring NC cells were measured to determine the average length and width of the bridge. (C-F) Selected images from a typical confocal time-lapse imaging session of individual NC cells (identified by separate nuclear cell label) in contact that displayed no cytoplasmic transfer between cells after photoconversion of KikGR (subregion marked by box). These images are from an in vitro experiment but similar results for both in vitro and in vivo were found. The images show the movement of photoconverted molecules (red) to the point of contact (arrowhead) between the cells. (I-L) Selected images from a typical confocal time-lapse imaging session of individual NC cells (identified by nuclear label) in contact that displayed cytoplasmic transfer. The images show the movement of photoconverted molecules (red) into a neighboring NC cell through a cellular bridge (arrow and arrowhead). These images are from an in vivo experiment but cytoplasmic transfer can also be seen in recently divided cells in vitro. Each NC cell nucleus is approximately 10um. See Supplemental Movies for more examples.