Mammalian dentitions are highly patterned, with different types of teeth positioned in regions the jaws. BMP4 is an early oral epithelial protein signal that directs odontogenic gene expression mesenchyme cells developing mandibular arch. was shown to inhibit homeobox Barx-1 and restrict proximal, presumptive molar mouse embryos at embryonic day 10. The inhibition BMP signaling mandible development by action exogenous Noggin resulted ectopic distal, incisor a transformation tooth identity from molar.

LIM-homeobox containing (Lhx) genes encode trascriptional regulators which play critical roles in a variety of developmental processes. We have identified two belonging to novel subfamily mammalian Lhx genes, designated Lhx6 and Lhx7. Whole-mount situ hybridisation showed that Lhx7 were expressed during mouse embryogenesis overlapping domains the first branchial arch basal forebrain. More specifically, expression was detected prior initiation tooth formation presumptive oral odontogenic...

Classical embryological experiments suggest that a posterior signal is required for patterning the developing anteroposterior axis. In this paper, we investigate potential role FGF signalling in process. During normal development, embryonic fibroblast growth factor (eFGF) expressed of Xenopus embryo. We have previously shown overexpression eFGF from start gastrulation results posteriorised phenotype reduced head and enlarged proctodaeum. now determined molecular basis propose patterning....

ABSTRACT The molecular events of odontogenic induction are beginning to be elucidated, but until now nothing was known about the basis patterning dentition. A role for Dlx-1 and Dlx-2 genes in dentition has been proposed with envisaged as participating an ‘odontogenic homeobox gene code’ by specifying molar development. This proposal based on restricted expression ectomesenchyme derived from cranial neural crest cells prior tooth initiation. Mice targeted null mutations both do not develop...

ABSTRACT In mammals, rostral ectomesenchyme cells of the mandibular arch give rise to odontogenic cells, while more caudal form distal skeletal elements lower jaw. Signals from epithelium are required for development and skeletogenic mesenchyme cells. We show that rostral-caudal polarity is first established in branchial ectomesenchymal by a signal, Fgf-8, epithelium. All neural crest-derived equicompetent respond Fgf-8. The restriction into (Lhx-7-expressing) (Gsc-expressing) domains...

Development of the mammalian tooth has been intensively studied as a model system for epithelial/mesenchymal interactions during organogenesis, and progress made in identifying key molecules involved this signaling. We show that activin βA is expressed presumptive tooth-germ mesenchyme thus candidate signaling molecule development. Analysis development mutant embryos shows incisor mandibular molar teeth fail to develop beyond bud stage. Activin an essential component maxillary molars,...

tabby and downless mutant mice have apparently identical defects in teeth, hair sweat glands. Recently, genes responsible for these spontaneous mutations been identified. (Dl) encodes Edar, a novel member of the tumour necrosis factor (TNF) receptor family, containing characteristic extracellular cysteine rich fold, single transmembrane region death homology domain close to C terminus. (Ta) ectodysplasin-A (Eda) type II membrane protein TNF ligand family an internal collagen-like domain. As...

Overexpression of Hoxa2 in the chick first branchial arch leads to a transformation cartilages, such as Meckel's and quadrate, into second elements, tongue skeleton. These duplicated elements are fused original similar manner that seen knockout, where reverse morphology is observed. This confirms role selector gene specifying fate. When neural crest alone targeted, lost, but Hoxa2-expressing unable develop elements. not due preventing differentiation cartilages. Upregulation marker arch,...

The cellular origin of the instructive information for hard tissue patterning jaws has been subject a long-standing controversy. Are cranial neural crest cells prepatterned or does epithelium pattern developmentally uncommitted population ectomesenchymal cells? In order to understand more about how orofacial is controlled we have investigated temporal signalling interactions and responses between mesenchymal in mandibular maxillary primordia. We show that within arch, homeobox genes are...

Abstract Having three ossicles in the middle ear is one of defining features mammals. All reptiles and birds have only ossicle, stapes or columella. How these two additional came to reside function mammals has been studied for last 200 years represents classic example how structures can change during evolution new novel ways. From fossil data, comparative anatomy developmental biology it now clear that bones mammalian ear, malleus incus, are homologous quadrate articular, which form...

The contribution of the endoderm to oral tissues head has been debated for many years. With arrival Cre/LoxP technology progenitor cells can now be genetically labeled and derived from traced. Using Sox17-2A-iCre/Rosa26 reporter mice we have followed fate in teeth, glands, taste papillae cavity.No was observed at any stage tooth development, or development major salivary mouse during development. In contrast, minor mucous glands tongue were found endodermal origin, along with circumvallate...

A central issue in biology concerns the presence, timing and nature of phylotypic periods development, but whether, when why species exhibit conserved morphologies remains unresolved. Here, we construct a developmental morphospace to show that amniote faces share period reduced shape variance convergent growth trajectories from prominence formation through fusion, after which phenotypic diversity sharply increases. We predict silico outcomes unoccupied morphospaces experimentally validate...

Salivary glands are formed by branching morphogenesis with epithelial progenitors forming a network of ducts and acini (secretory cells). During this process, specialise into distal (tips the gland) proximal (the stalk region) identities that produce higher order respectively. Little is known about factors regulate progenitor expansion specialisation in different parts gland. Here we show Sox9 involved establishing identity compartment before initiation morphogenesis. expressed throughout...

Tooth development is regulated by a reciprocal series of epithelial-mesenchymal interactions. Bmp4 has been identified as candidate signalling molecule in these interactions, initially an epithelial signal and then later at the bud stage mesenchymal (Vainio et al. [1993] Cell 75:45–58). A target gene for homeobox Msx-1, ability recombinant protein to induce expression mesenchyme. There is, however, no evidence that endogenous inducer Msx-1 expression. Bmp-4 show dynamic, interactive patterns...