Ossicle (echinoderm) - Wikipedia
Ossicles are small calcareous elements embedded in the dermis of the body wall of echinoderms. They form part of the endoskeleton and provide rigidity and protection. They are found in different forms and arrangements in sea urchins , starfish , brittle stars , sea cucumbers , and crinoids .
The ultrastructure and formation of the calcareous ossicles in the …
The calcareous ossicles of the burrowing sea cucumber Leptosynapta clarki have been examined by scanning and transmission electron microscopy. The ossicles occur in the dermis of the body wall and comprise three main types: 1) curved rods; 2) miliary granules; and 3) anchorshaped structures that are paired with oval plates.
The fine structure and development of calcified skeletal elements …
The calcareous ossicles and iron-rich calcified granules in the integument of sea cucumbers (Echinodermata: Holothuroida) have been examined by light and electron microscopy. Most ossicles are perforated, platelike structures that measure 100-500 μm long and consist of magnesium-rich calcite.
Echinoderm - Radial Symmetry, Tube Feet, Spines | Britannica
2024年11月14日 · The complex feeding apparatus (Aristotle’s lantern) of echinoids consists of 40 ossicles held together by muscles and collagenous sutures. Crinoids have a hollow sheath (theca or calyx) composed of two or three whorls, each consisting of five skeletal plates; the stalk and the slender appendages (cirri) of unstalked forms consist of a series ...
Ossicles - an overview | ScienceDirect Topics
Calcareous elements, called ossicles, are buried in the connective tissue of the body wall, forming the endoskeleton. Ossicles are a key feature in the taxonomic classification of holothuroids (Sui, 1988) (see Chapter 3 for details).
Morphology, shape variation and movement of skeletal elements …
Starfish (order: Asteroidea) possess a complex endoskeleton composed of thousands of calcareous ossicles. These ossicles are embedded in a body wall mostly consisting of a complex collagen fiber array. The combination of soft and hard tissue provides a challenge for detailed morphological and histological studies.
Summary. The calcareous ossicles of the burrowing sea cu- cumber Leptosynapta clarki have been examined by scan- ning and transmission electron microscopy. The ossicles oc- cur in the dermis of the body wall and comprise three main types: 1) …
Echinoderms as Blueprints for Biocalcification: Regulation of ...
2011年1月1日 · Adult sea urchins have several calcified structures, including test, teeth, and spines, composed of numerous ossicles which form a three-dimensional meshwork of mineral trabeculae, the stereom. The biomineral development begins in 24-hour-old embryos within the primary mesenchyme cells (PMCs), the only cells producing a set of necessary matrix ...
The ultrastructure and formation of the calcareous ossicles in the …
The calcareous ossicles of the burrowing sea cucumber Leptosynapta clarki have been examined by scanning and transmission electron microscopy and appear to be surrounded by a syncytial network of sclerocytes that characteristically possess numerous mitochondria and a conspicuous external lamina.
15.9: Phylum Echinodermata - Geosciences LibreTexts
2021年1月20日 · The Phylum Echinodermata is distinguished by characteristics such as spiny-skin, pentaradial symmetry, and an endoskeleton composed of calcareous ossicles. Given that all species in this phylum are exclusively marine dwellers, they also evolved a specialized water-vascular system.