Developmental Biology AER中FGF8的表达是肢体生长所必需的 iC) Figure 18.16 FGFS and limb morphogenesis. (A) In situ hybridization showing expression of [8 message in the ectoderm as the limb bud begins to form. (B) Expression of Fsfs RNA in the apical ectodermal ridge, the source of mitotic signals to the underlying mesoderm. ( C) In normal chick embryos(stage 17; roughly 24 hours), FGIS is ex- pressed in the apical ectodermal ridge of both the forelimb and hindlimb buds. It is also expressed in several other places in the embryo. (D)In the limbless mutant of chickens, FGFS is not expressed in the limb buds, although it is not lost in other embryonic regions. Here, the limb buds form but fail to develop into limbs
Developmental Biology AER中FGF8的表达是肢体生长所必需的
Developmental Biology 肢芽形成中的分子互作模型 Stage 16 Stage 17 Stage 18- 4⑤ Fgf8 induced AER BFgfIo (Fibroblast growth factor) by Fgf10 Proliferation Proliferation shh(sonic hedgehog Fgf10 maintained maintained 口Fg4+FgR8 by FGF8 by FGF8 Anterior FGF4 3(20 Posterior hh F8/4 induced maintained induced by FGF8 by FGF8+ by Shh FGF4 Somites Intermediate Lateral plate Surface mesoderm mesoderm ectoderm Figure 16.13 A molecular model for the initiation of the limb bud. FGF10 secreted by the lateral plate mesoderm induces FGF8 expression in the competent ectoderm at the dorsal-ventral bound ary. The anterior-posterior boundary is present at stage 16(and perhaps earlier). The FGF8 secretion by the ectoderm induces the proliferation of the mesenchy me cells and induces Sonic hedgehog expression in the posterior region of the limb bud. Sonic hedgehog induces FGf4 expression in the posterior portion of the limb bud ectoderm FGF2 is also made by the AER ectoderm, although it is not yet clear whether it is induced by the FGF10
Developmental Biology 肢芽形成中的分子互作模型
Developmenta 二、肢体近一远端轴幾的生成 AER在肢芽沿P一D轴线生长中的作用 AER 说明AER是维持间质 Limb development ceases 细胞分裂、推动肢体 向外生长所必需的 Extra AER 说明AER影响A-P轴 线 Forelimb AER mesoderm 说明间质细胞决定了 Leg mesoderm 肢体的类型 AER sses limb development ceases 说明间质细胞是维持 mesoderm AER所必需的 Figure 18.11 Summary of the effect of the apical ecto- dermal ridge(AER)on the underlying mesenchyme. (Modified from Wessells
Developmental Biology AER在肢芽沿P－D轴线生长中的作用 说明AER是维持间质 细胞分裂、推动肢体 向外生长所必需的 说明AER影响A-P轴 线 说明间质细胞决定了 肢体的类型 说明间质细胞是维持 AER所必需的 二、肢体近－远端轴线的生成
Developmental Biology AER维持间质细胞的分裂能力、防止其形成软骨: 去除AER中将分化为脚趾间组织的细胞,将形成额外的脚趾。 Figure 18.12 Cross section through the distal region that would form interdigital tissue. of a chick limb 3 days after a wedge of Instead of degenerating, the remaining the aer was removed from the area interdigital tissue formed an extra digit
Developmental Biology AER维持间质细胞的分裂能力、防止其形成软骨： 去除AER中将分化为脚趾间组织的细胞，将形成额外的脚趾
Developmental biology 鸡的两套趾症源于肢芽上有两个AER Figure 18 18 AER. It has recently been shown Cross sections of hindlimb buds from (Laufer et al. 1997) that two patches eudiplopodia chick embryos. (A)Two of radical fringe emerge on the limb AERs on hindlimb bud; extra out buds of this mutant, and each be. growth on the dorsal side will fo orm comes associated with the new AER an extra set of toes.( B)Both out- (From Goetinck, 1964, courtesy of P. growth regions are covered by an Goetinck
Developmental Biology 鸡的两套趾症源于肢芽上有两个AER