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Head morphogenesis
About: Head morphogenesis is a research topic. Over the lifetime, 134 publications have been published within this topic receiving 238681 citations.
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TL;DR: Using an improved method of gel electrophoresis, many hitherto unknown proteins have been found in bacteriophage T4 and some of these have been identified with specific gene products.
Abstract: Using an improved method of gel electrophoresis, many hitherto unknown proteins have been found in bacteriophage T4 and some of these have been identified with specific gene products. Four major components of the head are cleaved during the process of assembly, apparently after the precursor proteins have assembled into some large intermediate structure.
232,912 citations
TL;DR: Pulse-chase experiments in wild-type and mutant phage-infected cells provide evidence that the following particles called prohead I, II and III are successive precursors to the mature heads as discussed by the authors.
3,697 citations
TL;DR: The findings indicate that the endoderm instructs neural crest cells as to the size, shape and position of all the facial skeletal elements, whether they are cartilage or membrane bones.
Abstract: The vertebrate face contains bones that differentiate from mesenchymal cells of neural crest origin, which colonize the median nasofrontal bud and the first branchial arches. The patterning of individual facial bones and their relative positions occurs through mechanisms that remained elusive. During the early stages of head morphogenesis, an endodermal cul-de-sac, destined to become Sessel's pouch, underlies the nasofrontal bud. Reiterative outpocketings of the foregut then form the branchial pouches. We have tested the capacity of endoderm of the avian neurula to specify the facial skeleton by performing ablations or grafts of defined endodermal regions. Neural crest cells that do not express Hox genes respond to patterning cues produced regionally in the anterior endoderm to yield distinct skeletal components of the upper face and jaws. However, Hox-expressing neural crest cells do not respond to these cues. Bone orientation is likewise dependent on the position of the endoderm relative to the embryonic axes. Our findings thus indicate that the endoderm instructs neural crest cells as to the size, shape and position of all the facial skeletal elements, whether they are cartilage or membrane bones.
402 citations
TL;DR: The physiological manifestation of conditional lethal mutations in the genes involved in the formation of the T4 head have been re-examined in this paper, where the minimum number of head genes whose active product is needed to form the various head-related structures has been determined by examining infection by a series of double mutants.
378 citations
TL;DR: The findings, which elucidate the molecular basis of a complex Mendelian disorder, reveal the fundamental pleiotropic role played by a single factor that tightly coordinates brain development and skull shaping during head morphogenesis.
Abstract: Studies of genetically engineered flies and mice have revealed the role that orthologs of the human LIM homeobox LHX4 have in the control of motor-neuron–identity assignment and in pituitary development. Remarkably, these mouse strains, which bear a targeted modification of Lhx4 in the heterozygous state, are asymptomatic, whereas homozygous animals die shortly after birth. Nevertheless, we have isolated the human LHX4 gene, as well as the corresponding cDNA sequence, to test whether it could be involved in developmental defects of the human pituitary region. LHX4, which encodes a protein 99% identical to its murine counterpart, consists of six coding exons and spans >45 kb of the q25 region of chromosome 1. We report a family with an LHX4 germline splice-site mutation that results in a disease phenotype characterized by short stature and by pituitary and hindbrain (i.e., cerebellar) defects in combination with abnormalities of the sella turcica of the central skull base. This intronic mutation, which segregates in a dominant and fully penetrant manner over three generations, abolishes normal LHX4 splicing and activates two exonic cryptic splice sites, thereby predicting two different proteins deleted in their homeodomain sequence. These findings, which elucidate the molecular basis of a complex Mendelian disorder, reveal the fundamental pleiotropic role played by a single factor that tightly coordinates brain development and skull shaping during head morphogenesis.
255 citations