Body Spicules Research Articles

New data on nudibranchs rhinophore morphology and their spicule complex in Onchidoris muricata (Doridina, Gastropoda)

Nudibranchia is a group of shell-less heterobranch gastropods characterized by highly specialized chemosensory cephalic organs known as rhinophores. Whereas the morphology of the rhinophore is an important taxonomic character, as the external structures are used when describing species. However, the internal morphology of the rhinophore has only been studied in terms of neurophysiology. In this study, for the first time, the external and internal structure of the rhinophore in Onchidoris muricata (O.F. Müller, 1776) is described in detail using methods of light, scanning electron-, transmission electron- and confocal laser scanning microscopy, as well as computer microtomography (micro-CT).Data obtained showed that spicules of the rhinophore significantly differ from the body spicules in both general morphology and localization. The thinner and longer spicules of the rhinophore form the spiral square mesh network, allowing mobility which permits contraction of the rhinophore while maintaining a strong framework. Interestingly, the ultrathin structure of the spicules and scleroblasts resemble those of the body spicules. The lymphatic canal and the large nerve and associated longitudinal muscles are situated in the central part of the rhinophore. Stemming from the large nerve are thin transverse muscles and nerve branches associated with the rhinophore lamellae. Morphological analyses suggest a lymphatically driven mechanism in O. muricata, which is capable of quick muscular contraction and slow retraction of the rhinophore.

A note on five freshwater sponges (Porifera: Spongillina: Spongillidae) from Pune, Maharashtra, India

We report the presence of five freshwater sponges in ephemeral and permanent fresh water bodies in and around Pune, Maharashtra, India. Field observations, descriptive notes, habitus photographs and SEM photographs of body spicules, gemmule spicules and gemmules of five species are provided. Eunapius carteri (Bowerbank, 1863), Radiospongilla cerebellata (Bowerbank, 1863) and Corvospongilla lapidosa (Annandale, 1908) are commonly occurring species, whereas Ephydatia meyeni (Carter, 1849) and Dosilia plumosa (Carter, 1849) are rarely found. This report fills a longstanding gap in observations of freshwater sponges near Pune, and it is heartening to note that species reported earlier are still found in these environs.

Induction of cell migration and activation in mice by the freshwater sponge Drulia uruguayensis Bonetto & Ezcurra de Drago, 1968 (Porifera: Metaniidae)

Freshwater sponges are abundant in the Amazon region and they have been known to cause dermatitis (acute inflammation) since the beginning of the 20th century. To determine whether additional constituents, besides their body spicules, cause dermatological reactions in humans, an experimental study was developed and carried out using mice and Drulia uruguayensis prepared in three different forms: intact sponges (IS), macerated sponges (MS) or isolated spicules - megascleres (ISM). The cells most commonly involved in inflammatory reactions (mast cells, eosinophils and neutrophils), as well as intraepithelial lymphocytes and degranulated mast cells, were counted so that they could be used as parameters to determine which of the sponge preparations induced the greatest reaction. The effects of the sponge on the skin were then determined by histological analysis. The results obtained showed that IS caused the greatest inflammatory reaction (p = 0.000005), activating mainly mast cells (p = 0.0018). The histopathological analysis revealed a slight loss of continuity of the epidermis when ISM or IS were applied. These findings allow us to conclude that a structurally intact sponge can cause a greater inflammatory reaction in the first contact because of its ability to perforate the skin and allow inflammatory agents to enter. Other proteins present in dried sponge bodies could induce allergic but not toxic responses (in contact with the entire sponge, a large number of pharmacologically inert proteins may be introduced, with a potential allergen).

First articulated Silurian sponges from the Iberian Peninsula (Spain and Portugal)

The first-described articulated Silurian sponges from Spain and Portugal include a moderate assemblage of hexactinellids and a single monaxonid demosponge. The sponges were collected from a thin layer at the top of theCyrtograptus lundgreni-Monograptus testisgraptolite biozone, in a possible volcanic ash of latest Homerian (Wenlock) age. The sponges are from southeastern Portugal and southwestern Spain in the Ossa-Morena Zone of the Hesperian Massif. The hexactinellid collection includes several specimens of the new species,Protospongia iberica,and fragments ofDiagoniellaspecies andGabelia(?) sp. Specimens of the latter two taxa are too small for species identification. Demosponges are represented by a single described specimen of a probably new genus and species preserved as a “wreath” of monaxon spicules. Dermal and gastral layers are of very fine spicules developed over the moderately coarse, aligned, principal body spicules.

Ultrastructural Aspects of Spicule Formation in the Solitary Ascidian Herdmania momus (Urochordata, Ascidiacea)

AbstractThe solitary stolidobranch ascidian Herdmania momus contains numerous calcium carbonate spicules in its tunic and body tissues. The slender body spicules form inside complex sheaths in the body wall and branchial basket, where they remain for the life of the animal. The much smaller tunic spicules form inside the tunic blood vessels and then migrate to the tunic surface, where they become anchored by their spiny base. This paper is an ultrastructural investigation of the formation of the body spicules; the tunic spicules, which apparently form quite differently, will be the focus of a future study. The body spicules are composed of rows of closely packed acicular spines which form completely extracellularly. The spine tips are covered by flattened, highly pseudopodial sclerocytes bound together by tightly interdigitating cell processes. The basal regions of contiguous spines are covered by very thin sclerocyte cell processes. An organic matrix is present within the spines; its exact nature is not clear. A very dense extracellular inter‐spine matrix is located between the spine tips and the contiguous basal regions. Presclerocytes within the sheaths between the spicules are probably responsible for formation of the extracellular structures of the sheaths. The presclerocytes appear to aggregate and transform into sclerocytes at the apical end of the spicule. New spines are added at the apical end of the spicule as well as between larger spines. Comparisons are made between body spicule formation in H. momus and skeletogenesis in echinoids.

Spicule formation in the solitary ascidian, herdmania momus.

Two types of calcareous spicules occur abundantly in Herdmania momus, a solitary pyurid ascidian with a worldwide warm water distribution. The large spindle-shaped body spicules are 1.5-2.5-mm long and are located primarily in the mantle, siphons, and branchial basket. Each body spicule possesses 100 or more rows of overlapping, unidirectional fringing spines. Numerous body spicules occur regularly spaced within a long common sheath of complex structure, and there are many sheaths per animal. Between neighboring body spicules and overlying the fringing spines are the tightly connected pseudopodial sclerocytes. Spine formation is hypothesized to occur within these cells. The body spicules apparently continue to increase in size throughout the animal's life. The tunic spicules are about one tenth the length of the body spicules. They have 20-40 rows of unidirectional nonoverlapping fringing spines and a mace-shaped spiny base that anchors them at the tunic surface. They form quickly in individual spicular envelopes inside the tunic blood vessels over a 4-5-day period. Each tunic spicule then leaves its surrounding envelope and blood vessel, passes into the tunic, and ultimately protrudes through the outer surface of the tunic. An organic covering inside the envelope closely adheres to the tunic spicules and stains with toluidine blue. Dissolution of the CaCO3 mineral phase by EDTA or EDTA-cetylpyridinium chloride-formaldehyde reveals an intricately patterned organic matrix within or upon which the spicules develop.