During bending of the neural plate, the neural folds undergo two types of movements which ultimately bring them together in the dorsal midline and enable subsequent fusion: (1) dorsad elevation and (2) mediad convergence. Such movements require both intrinsic forces (i.e., forces generated within the neural plate) and extrinsic forces (i.e., forces generated by tissues outside the neural plate) acting in concert. However, the factors) that controls the directionality of neural fold movements is currently unknown. The present study investigates the role of the neural plate/epidermal ectoderm (NP/EE) transition zone (i.e., the prospective interface of the neural fold) in this process. To do this, we examined the neuroepithelium or epidermis of post-incubation chick embryos into which isochronic, fluorescently-labeled plugs of chick neural plate, epidermal ectoderm, or NP/EE transition zone were placed at stages 5 and 6. Transverse sections through such embryos revealed that neural folds formed at the interface in NP/EE transition zone grafts, regardless of the site of grafting and initial graft orientation in the host embryo. Ectopic neural folds also formed along newly created interfaces between NP and EE; however, only ectopic neural folds that formed on the original medial side of the transplanted EE underwent full elevation and convergence. We conclude that the NP/EE transition zone plays a pivotal role in organizing and directing dorsad and mediad neural fold movements during bending but does not actively generate the forces that drive these processes.
|Original language||English (US)|
|State||Published - Dec 1 1997|
ASJC Scopus subject areas
- Molecular Biology