The cellular basis of photobehavior in the tufted parenchymella
larva of demosponges.
A variety of unusual embryos exist in sponges (e.g., parenchymella, amphiblastula; Fig.
While a parenchymella of a sponge is not directly comparable in structure to the gastrula of an echinoderm, the migration of cells into the core of the parenchymella in the sphinctozooid sponge Vaceletia (=Neocoelia, Simpson, 1984, p.
Although patterning processes appear to be less complex in this sponge than in bilaterians (Adamska et al., 2007a,b), gastrulation, patterning, and differentiation events in Amphimedon give rise to a radially symmetrical parenchymella
larva with 3 cell layers, at least 11 differentiated cell types, and a tissue-like structure, the photoreceptor pigment ring (Leys and Degnan, 2002).
This paper addresses the ontogenetic change in the light response and its cytological basis in the parenchymella larva of the demosponge Reneira sp.
A radial or circumferential sheath has been described in many parenchymella larvae as a subepithelial cell layer (Meewis, 1941; Brien, 1973; Woollacott, 1993).
An amphiblastula or coeloblastula is produced by calcareous sponges; a parenchymella is the larva of the majority of demosponges, but several other larval types are known; and a trichimella is exclusive to hexactinellid sponges.
Ultrastructure de la larve parenchymella d'Hamigera hamigera (Schmidt) (Demosponge, Poeciloscierida).
In Demospongiae, several authors have suggested that the coeloblastula or parenchymella
larvae express an existing polarity in their attachment to the substrate.
The free-swimming parenchymella
larvae of Haliclona permollis are about 250 [[micro]meter] in length and 180 [[micro]meter] in width.
Large oocytes (393 [+ or -] 91 [[micro]meter]) are fertilized internally and are incubated until they develop into mature parenchymella
larvae [ILLUSTRATION FOR FIGURE 3D OMITTED].