Fgf8 functions as an organizer at the mes/metencephalic boundary (isthmus). We showed that a strong Fgf8 signal activates the Ras-ERK signaling pathway to organize cerebellar differentiation. Sprouty2 is expressed in an overlapping manner to Fgf8, and is induced by Fgf8. Its function, however, is indicated to antagonize Ras-ERK signaling. Here, we show the regulation of Fgf8 signaling in relati...

We provide evidence that FGF8 serves as an endogenous inducer of chick limb formation and that its expression in the intermediate mesoderm at the appropriate time and place to trigger forelimb development is directly linked to the mechanism of embryonic kidney differentiation. One function of the limb inducer is to initiate Fgf8 gene expression in the ectoderm overlying the prospective limb-for...

When a tubular structure forms during early embryogenesis, tubular elongation and lumen formation (epithelialization) proceed simultaneously in a spatiotemporally coordinated manner. We here demonstrate, using the Wolffian duct (WD) of early chicken embryos, that this coordination is regulated by the expression of FGF8, which shifts posteriorly during body axis elongation. FGF8 acts as a chemoa...

The vertebrate inner ear develops from initially 'simple' ectodermal placode and vesicle stages into the complex three-dimensional structure which is necessary for the senses of hearing and equilibrium. Although the main morphological events in vertebrate inner ear development are known, the genetic mechanisms controlling them are scarcely understood. Previous studies have suggested that the ot...

Fibroblast growth factor (Fgf) 8 is essential for the development of multiple brain regions. Previous studies from our laboratory showed that reduced Fgf8 signaling led to the developmental alterations of neuroendocrine nuclei that originated within the diencephalon, including the paraventricular (PVN) and supraoptic (SON) nuclei. To further understand the role of Fgf8 in the development of oth...

Members of the fibroblast growth factor (Fgf) family are important signaling molecules in several inductive and patterning processes, and act as brain organizer-derived signals during formation of the early vertebrate nervous system. We isolated a new member of the Fgf8/17/18 subgroup of Fgfs from the zebrafish, and studied its expression and function during somitogenesis, optic stalk and midbr...

Recent findings implicate embryonic signaling centers in patterning the mammalian cerebral cortex. We used mouse in utero electroporation and mutant analysis to test whether cortical signaling sources interact to regulate one another. We identified interactions between the cortical hem, rich in Wingless-Int (WNT) proteins and bone morphogenetic proteins (BMPs), and an anterior telencephalic sou...

Mammalian oocytes are deficient in their ability to carry out glycolysis. Therefore, the products of glycolysis that are necessary for oocyte development are provided to oocytes by companion cumulus cells. Mouse oocytes secrete paracrine factors that promote glycolysis in cumulus cells. The objective of this study was to identify paracrine factors secreted by oocytes that promote glycolysis and...

Fgf8 exerts a strong effect on the mesenchymal cells of neural crest (NC) origin that are fated to form the facial skeleton. Surgical extirpation of facial skeletogenic NC domain (including mid-diencephalon down through rhombomere 2), which does not express Hox genes, results in the failure of facial skeleton development and inhibition of the closure of the forebrain neural tube, while Fgf8 exp...

Several members of the FGF gene family have been shown to intervene from various tissue sources to direct otic placode induction and otic vesicle formation. In this study we define the roles of FGF8, found in different expression domains during this process, in mice and chickens. By conditional inactivation of Fgf8 in distinct tissue compartments we demonstrate that Fgf8 is required in the meso...