@entity34224 and XXXX are sequentially required for formation of the midbrain-hindbrain compartment boundary.

@entity8739 @entity8668 @entity19 @entity5005 @entity34224
In vertebrates, the common expression border of two homeobox genes, @entity5005 and @entity34224 , demarcates the prospective @entity8668 ( @entity8668 ) in the neural plate at the end of gastrulation. The presence of a compartment boundary at the @entity8668 has been demonstrated, but the mechanism and timing of its formation remain unclear. We show by genetic inducible fate mapping using a @entity34224 (CreER) knock-in @entity19 line that descendants of @entity34224 (+) cells as early as embryonic day (E) 7.5 do not cross the @entity8668 . Without @entity34224 , hindbrain-born cells abnormally populate the entire midbrain, demonstrating that @entity34224 is essential for specifying hindbrain fate. @entity34224 (+) and @entity5005 (+) cells segregate from each other, suggesting that mutually exclusive expression of @entity5005 and @entity34224 in midbrain and hindbrain progenitors is responsible for cell sorting in establishing the @entity8668 . The @entity8668 organizer gene @entity8739 , which is expressed as a sharp transverse band immediately posterior to the lineage boundary at the @entity8668 , is crucial in maintaining the lineage-restricted boundary after E7.5. Partial deletion of @entity8739 disrupts @entity8668 lineage separation. Activation of FGF pathways has a cell-autonomous effect on cell sorting in midbrain progenitors. Therefore, @entity8739 from the @entity8668 may signal the nearby mesencephalic cells to impart distinct cell surface characteristics or induce local cell-cell signaling, which consequently prevents cell movements across the @entity8668 . Our findings reveal the distinct function of @entity34224 and @entity8739 in a stepwise process in the development of the compartment boundary at the @entity8668 and that @entity8739 , in addition to its organizer function, plays a crucial role in maintaining the lineage boundary at the @entity8668 by restricting cell movement.
