Extended Data Figure 3: Identification of the forebrain–midbrain–hindbrain boundaries in early hagfish embryos.
From: Evidence from cyclostomes for complex regionalization of the ancestral vertebrate brain
a–c, The mid–hindbrain boundary (MHB) of the hagfish brain is assumed to correspond to the posterior expression boundary of OtxC (b) and focal expression of Fgf8/17 (see Extended Data Fig. 5) (c) that become evident at stages 28–30. a–d, On the other hand, the fore–midbrain boundary (FMB) is suggested morphologically (a, b) and by the ventrocaudal portion of Nkx2.1/2.4 expression domain (d, arrowheads). See Figs 1 and 2 for abbreviations. Scale bar, 200 μm.