Head development in the onychophoran Euperipatoides kanangrensis with particular reference to the central nervous system

  title={Head development in the onychophoran Euperipatoides kanangrensis with particular reference to the central nervous system},
  author={Bo Joakim Eriksson and Noel Norman Tait and Graham E. Budd},
  journal={Journal of Morphology},
The neuroectoderm of the Euperipatoides kanangrensis embryo becomes distinguishable during germ band formation when the antennal segment is evident externally. During later stages of development, the neuroectoderm proliferates extensively and, at the anterior part of the head, newly–formed neuron precursor cells occupy most of the volume. The antenna forms from the dorsolateral side of the anterior somite. The antenna has no neuroectoderm of its own at the onset of its formation, but instead… 

The fate of the onychophoran antenna

Data on early axogenesis in anostracan crustaceans show that even in the earliest embryos, before the antennula and antennal nerves are developed, the circumoral anlagen of the brain display very prominent nerves which run into the frontal filament organ (also known as the cavity receptor organ), which leads to conclude that the frontal filaments are indeed homologous to the primary antenna.

Axogenesis in the stomatopod crustacean Gonodactylaceus falcatus (Malacostraca)

Comparisons with other crustaceans and arthropods indicate homology of crustacean nauplius eyes, a circumoral deutocerebrum, and a more widespread occurrence of posterior pioneer neurons forming the axon scaffold of the ventral central nervous system than previously thought.

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The formation of the major axon pathways in the embryonic central and peripheral nervous systems of the amphipod crustacean Orchestia cavimana Heller, 1865 are described by means of antibody staining against acetylated alpha-tubulin and provide a basis for future studies of neurogenesis on a deeper cellular and molecular level.

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The innervation of the head was found to differ from that reported in earlier investigations, and the nerves that support the mouth were found to originate from three different regions of the brain, suggesting that present day onychophorans with a ventrally placed mouth, have evolved from an ancestor with a terminal mouth.

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The pycnogonid cluster-stream-systems show striking similarities to the life-long neurogenic system of decapod crustaceans, and due to their close vicinity to glomerulus-like neuropils, it is considered their possible involvement in post-embryonic (perhaps even adult) replenishment of olfactory neurons – as in decapods.

Expression of engrailed in the developing brain and appendages of the onychophoran euperipatoides kanangrensis (Reid).

It is suggested that onychophorans may have acquired two copies of engrailed with different functions, as engrailing transcripts were detected in a subset of developing neurons in the brain anlage, and in the mesoderm as well as ectoderm of the developing limb buds.

Neural development in the tardigrade Hypsibius dujardini based on anti-acetylated α-tubulin immunolabeling

The revealed pattern of brain development supports a single-segmented brain in tardigrades and challenges previous assignments of homology between tardigade brain lobes and arthropod brain segments.



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  • G. Budd
  • Biology, Geography
    Transactions of the Royal Society of Edinburgh: Earth Sciences
  • 1998
The combination of characters found in Kerygmachela allows it to be allied with the lobopods, represented in the extant fauna by the onychophorans, tardigrades, and possibly the pentastomids, and in the Cambrian fossil record by a morphologically diverse set of taxa, some of which are not assignable to the extant groupings.

Neurogenesis in the spider Cupiennius salei.

The results suggest that the basic processes of neurogenesis, as well as proneural gene function is conserved among arthropods, apart of the lack of neuroblast-like stem cells in spiders.

A conserved mode of head segmentation in arthropods revealed by the expression pattern of Hox genes in a spider.

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Foregut endoderm is required at head process stages for anteriormost neural patterning in chick.

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The transitory coelomic cavities of the onychophoran Epiperipatus biolleyi are investigated ultrastructurally and compared with data on the coelomogenesis of the polychaetous annelids Ophelia rathkei, Spirorbis spirorbis, and Pectinaria koreni.

Cell lineage studies in the crayfish Cherax destructor (Crustacea, Decapoda) : germ band formation, segmentation, and early neurogenesis

  • G. Scholtz
  • Biology
    Roux's archives of developmental biology
  • 2004
The cell division pattern of the germ band of Cherax destructor is described from gastrulation to segmentation, limb bud formation, and early neurogenesis, compared with the early development of other crustaceans and insects.

Axogenesis in the embryonic brain of the grasshopper Schistocerca gregaria: an identified cell analysis of early brain development.

The single cell analysis of grasshopper brain development presented here sets the stage for manipulative cell biological experiments and provides the basis for comparative molecular genetic studies of embryonic brain development in Drosophila.

The position of the Arthropoda in the phylogenetic system

There are morphological characters that support Articulata, but molecular as well as morphological data advocate Ecdysozoa, and comparative morphology suggests Gastrotricha as the sister group of Ecdy sozoa with the synapomorphies.

Comparison of early nerve cord development in insects and vertebrates.

It is widely held that the insect and vertebrate CNS evolved independently. This view is now challenged by the concept of dorsoventral axis inversion, which holds that ventral in insects corresponds