Organization of the coelomic lining and a juxtaposed nerve plexus in the suckered tube feet ofParastichopus californicus (Echinodermata: Holothuroida)

2005 ◽  
Vol 267 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Michael J. Cavey
Keyword(s):  
Nerve Plexus ◽  
Coelomic Lining ◽  
Tube Feet

scholarly journals The Histology and Activities of the Tube-feet of Echinocyamus pusillus

1959 ◽  
Vol s3-100 (52) ◽  
pp. 539-555
Author(s):  
DAVID NICHOLS
Keyword(s):  
Sea Urchin ◽  
Nerve Plexus ◽  
Asterias Rubens ◽  
Coelomic Epithelium ◽  
Sensory Cilia ◽  
Thin Walled ◽  
Postural Movement ◽  
Tube Feet

The histology of the suckered, buccal sensory, and respiratory tube-feet and their ampullae, where they occur, of the clypeasteroid sea-urchin Echinocyamus pusillus is described. Each suckered tube-foot possesses two sets of special muscles for attachment and detachment, a ring of mucous glands to assist in attachment, and a ring of sensory cilia. The stem retractors are in four columns, whose differential contraction provides the means of postural movement relative to the test. The ampullae of these tube-feet are exceedingly thin-walled, apparently musculo-epithelial, with anastomosing contractile elements. The canal between tube-foot and ampulla contains a swollen coelomic epithelium which may help to maintain the nerve relationships of the system. The activity of the suckered tube-feet is compared with that of the tubefeet of the starfish, Asterias rubens. The buccal tube-feet, larger than the suckered tube-feet, have large disks underlain by a thick nerve plexus supported by transverse fibres; a ring of sensory cilia surrounds the disk. They have no mucous glands and no suckers, and are presumably entirely sensory, probably both tactile (the cilia) and chemoreceptive (the disk). The respiratory tube-feet are thin-walled sacs, the walls consisting of an outer ciliated and an inner non-ciliated (coelomic) epithelium with cross-connexions for support; where the coelomic epithelium lines the pair of canals through the test it is heavily ciliated. In the specializations of its tube-feet this urchin is shown to share some features with the regular urchins and others with the spatangoids.

Organization of the adluminal and retractor cells in the coelomic lining from the tube foot of a phanerozonian starfish, Luidia foliolata

1991 ◽  
Vol 69 (4) ◽  
pp. 911-923 ◽  
Author(s):  
Michael J. Cavey ◽  
Richard L. Wood
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Connective Tissue ◽  
Basal Lamina ◽  
Freeze Fracture ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Primitive Species ◽  
Ultrathin Sections ◽  
Coelomic Lining ◽  
Tube Feet

The coelomic lining in the tube feet of the phanerozonian starfish Luidia foliolata is a complex pseudostratified myoepithelium consisting largely of flagellated adluminal cells and myofilament-bearing retractor cells. The adluminal cells, joined by zonular intermediate and septate junctions, line the water–vascular canal. Basal processes of the adluminal cells penetrate the underlying layers of retractor cells to terminate as bulbous pedicels at the myoepithelial basal lamina. The longitudinally oriented retractor cells, linked by macular and fascial intermediate junctions, also direct processes obliquely to the basal lamina for anchorage. In keeping with its myoepithelial classification, the coelomic lining of the tube foot is devoid of connective tissue. The organization of the coelomic lining in this primitive species has not substantively improved our understanding of the events of excitation–contraction coupling. Both the coelomic lining and the podial connective tissue lack nerves, and there is no ultrastructural evidence of communicating (gap) junctions between the retractor cells. The sarcoplasmic reticulum of a retractor cell is a plexiform network of agranular cisternae lodged between the contractile apparatus and the sarcolemma. Peripheral couplings between the sarcoplasmic reticulum and the sarcolemma can be identified in ultrathin sections by the presence of electron-dense plaques in the sarcoplasmic gaps between the apposed membranes. In freeze-fracture replicas, the placement of these structural couplings is correlated with aggregations of large intramembranous particles over regions of cisternal confluence. Conceptual problems in understanding excitation–contraction coupling in a modern starfish are compounded in this primitive representative by the presence of many more layers of retractor cells and by a burrowing life-style which requires the tube feet to respond in a rapid, highly coordinated manner.

scholarly journals Histologic Examination of a Sea Pig (Scotoplanes sp.) Using Bright Field Light Microscopy

2021 ◽  
Vol 9 (8) ◽  
pp. 848
Author(s):  
Elise E. B. LaDouceur ◽  
Linda A. Kuhnz ◽  
Christina Biggs ◽  
Alicia Bitondo ◽  
Megan Olhasso ◽  
...  
Keyword(s):  
Deep Sea ◽  
Body Wall ◽  
Monterey Bay ◽  
Bright Field ◽  
Male And Female ◽  
Rete Mirabile ◽  
Lateral Body ◽  
Bright Field Microscopy ◽  
Microscopic Findings ◽  
Tube Feet

Sea pigs (Scotoplanes spp.) are deep-sea dwelling sea cucumbers of the phylum Echinodermata, class Holothuroidea, and order Elasipodida. Few reports are available on the microscopic anatomy of these deep-sea animals. This study describes the histologic findings of two, wild, male and female Scotoplanes sp. collected from Monterey Bay, California. Microscopic findings were similar to other holothuroids, with a few notable exceptions. Sea pigs were bilaterally symmetrical with six pairs of greatly enlarged tube feet arising from the lateral body wall and oriented ventrally for walking. Neither a rete mirabile nor respiratory tree was identified, and the large tube feet may function in respiration. Dorsal papillae protrude from the bivium and are histologically similar to tube feet with a large, muscular water vascular canal in the center. There were 10 buccal tentacles, the epidermis of which was highly folded. Only a single gonad was present in each animal; both male and female had histologic evidence of active gametogenesis. In the male, a presumed protozoal cyst was identified in the aboral intestinal mucosa, and was histologically similar to previous reports of coccidians. This work provides control histology for future investigations of sea pigs and related animals using bright field microscopy.

Ultrastructure of nerve plexus in flatworms

1975 ◽  
Vol 157 (2) ◽  
Author(s):  
Harold Koopowitz ◽  
Paul Chien
Keyword(s):  
Nerve Plexus

The Mechanisms of Coordination of the Starfish Tube Feet

Behaviour ◽  
1954 ◽  
Vol 6 (1) ◽  
pp. 206-232 ◽  
Author(s):  
G.A. Kerkut
Keyword(s):  
Tube Feet
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