Intercalary

Breaks caused by chromosome aberrations in regions with repeats may not result in a sharp decline of viability, so that break points of chromosome rearrangements in intercalary heterochromatin may be more frequent than in other regions.

In this new model, the anterior and posterior blastemas were formed as signaling centers to direct intercalary reorganization of body regionality or positional information.

...two radial cells, second longer than first; intercalary fork fairly distinct; crossvein r-m vertical...