|
|
|
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 3. Inductive interactions that regulate otocyst induction and ventral
patterning. (A) Cross-section of a developing vertebrate embryo at the level
of rhombomeres 4 and 5. Prior to placodal induction, a group of transcription
factors, including Dlx3b, Dlx4b, Sox9a and Foxi1 are expressed in the
preplacodal ectoderm (blue). Simultaneously, the hindbrain (HB) secretes Fgf3
(green), which acts as an inducer for the otic placode. (B) At the same time,
periotic mesenchyme (POM) located between the hindbrain and placodal ectoderm
produces either Fgf10- or Fgf19/15- (red) inducing agents, depending on the
species. (C) The combined expression of Fgf3 (green) and either Fgf10 or
Fgf19/15 (red) generates a combinatorial code (yellow) that induces placodal
development in a specific region of the ectoderm (purple). (D) After closure
of the otocyst, ventral phenotypes are induced through a combination of the
expression of the transcription factor Six1 (orange) in the ventral region of
the otocyst and long-range signaling by Shh (pink). Shh originates in the
notochord and floorplate to influence the formation of both otocysts (although
the presumed signaling interactions are only illustrated for the left
side).
|
