Spicule formation in the calcareous sponge Sycon ciliatum

  title={Spicule formation in the calcareous sponge Sycon ciliatum},
  author={Philip W. Ledger and Walter Clifford Jones},
  journal={Cell and Tissue Research},
SummaryThe spicule primordium is formed in an intercellular cavity within a group of sclerocytes. This cavity contains organic material which ensheaths the growing spicule but does not appear to determine the nature of the mineral morph (magnesian calcite) or the crystallographic orientation of the spicule. The tip of each growing spicule ray is seated in a ‘dense cup’ in the cytoplasm of the sclerocyte concerned. Both ends of monaxons are initially inserted each into a dense cup. As rays… 

Calcification of the collagenous axial skeleton of Veretillum cynomorium pall. (cnidaria: pennatulacea)

The axial skeletal rod of Veretillum cynomorium consists of a fibrillar collagenous matrix calcified with calcite which exhibits a distinctive microarchitecture which can be related to the predominantly c-axis parallel growth of the calcite.

Crystallographic orientation and concentric layers in spicules of calcareous sponges.

Mineral skeletogenesis in sponges 1

Sponges secrete a variety of mineral skeletons consisting of calcite, aragonite, and (or) amorphous silica that confer strength and protect them from physical perturbations. Calcification takes place

Spicule form in calcareous sponges porifera calcarea the principle of uniplanar curvature

A study of the shapes of secondary sagittal tri- and quadri-radiate spicules of the calcareous sponge Leuconia fistulosa has revealed that the paired rays appear kinked, with straight sections in

Comparative study of spiculogenesis in demosponge and hexactinellid larvae

  • S. Leys
  • Biology
    Microscopy research and technique
  • 2003
The elaboration and organization of the spicules differ markedly in cellular and syncytial sponges and appear to be an outcome of the very distinct cellular differentiation and larval morphogenesis that occur in each of these groups.

Spicule formation in calcareous sponges: Coordinated expression of biomineralization genes and spicule-type specific genes

Five additional biomineralization genes in Sycon ciliatum are identified and it is suggested that spicule formation is controlled by defined temporal and spatial expression of spicules-type specific sets of biominalization genes.

Phylogeny and evolution of calcareous sponges

The most recent advances concerning the phylogeny and evolution of calcareous sponges (Calcarea or Calcispongia) are reviewed here, in the light of the history of taxonomy of the group and



Crystalline Properties of Spicules of Leucosolenia complicata

The spicule form can be explained by a combination of extrinsic and intrinsic factors, the latter depending on the properties of the crystallizing material, the former on the gene complex.

The Sheath of Spicules of Leucosolenia complicata

Corrosion by potash solution produces a rigid, brittle ‘sheath’, which consists of the true sheath and an inorganic deposit laid down on its inner surface as the calcite dissolves away, whereas in hydrochloric and carbonic acid solutions the calcites dissolves uniformly all round the rays.

Memoirs: Materials for a Monograph of the Ascons.--I. On the Origin and Growth of the Triradiate and Quadriradiate Spicules in the Family Clathrinidæ

The forms of the spicules are the result of adaptation to the requirements of the sponge as a whole, produced by the action of natural selection upon variation in every direction.

Calcareous sponge spicules: A study of magnesian calcites

The results of chemical, X-ray diffraction and infra-red analyses, together with specific gravity determinations, are presented for the spicules of seven species of Calcarea. The spicules are

Sheath and Axial Filament of Calcareous Sponge Spicules

Stain reactions and electron microscopy indicate that the characteristic crystallographic structure of the sponge spicules is not the result of the growth of calcite over an organic precursor, but of inorganically impure calcite.

Spicule Form in Leucosolenia complicata

The tri- and quadriradiates of Leucosolenia complicata are described in four aspects: surface view, transverse view, side view, and planar view. The spicule form and size vary with the distance from

The Comparative Ultrastructure and Organization of Five Calcified Tissues

The organic matrices of vertebrate mineralized tissues characteristically contain deposited calcium phosphate as more poorly crystalline hydroxyapatite, as in bone (Glimcher, 1959; Glimcher et al., 1960), or in more highly crystalline form,As in enamel (Travis and Glimchers, 1964).