BIOLOGY OF HYDRACTINIID HYDROIDS. 4. ULTRASTRUCTURE OF THE PLANULA OF<i>HYDRACTINIA ECHINATA</i>

Weis, Virginia M.; Keene, Douglas R.; Buss, Leo W.

doi:10.2307/1541521

Cited by 52 publications

(43 citation statements)

References 29 publications

(30 reference statements)

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“…Therefore we used planula migration (Müller, 1969) as an alternative assay for muscle activity. The planula of Hydractinia is covered by ciliated epitheliomuscular cells (Weis et al, 1985). We presume that ciliary activity is the basis for planula migration.…”

Section: Hydractinia Echinatamentioning

confidence: 89%

Control of planula migration by LWamide and RFamide neuropeptides inHydractinia echinata

Katsukura

Andō

David

et al. 2004

Journal of Experimental Biology

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Section: Hydractinia Echinatamentioning

confidence: 89%

Control of planula migration by LWamide and RFamide neuropeptides inHydractinia echinata

Katsukura

Andō

David

et al. 2004

Journal of Experimental Biology

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“…Moreover, the cells lacked extended membrane areas, which would be indicative of photoreceptive cells. Sensory cells carrying a recessed cilium not associated with microvilli have been described for several Hydrozoa (Jha and Mackie, 1967;Weis et al, 1985;Thomas et al, 1987). They are most plausibly considered chemoreceptive (Kass-Simon and Hufnagel, 1992).…”

Section: Sensory Featuresmentioning

confidence: 99%

“…Also, the apical "pigment granules" described for several sensory cells (Weis et al, 1985;Westfall and Kinnamon, 1978) may be checked for a secretory function. There is much evidence indicating that the most conspicuous apical organelle of cnidarian epidermal cells, the cnidocyst, is also a highly developed secretory vesicle (for review, see Tardent, 1995) and that its discharge is a rapid (voltage-and calcium-dependent) exocytotic secretion similar to that of synaptic vesicles (Gitter et al, 1994, Gitter andThurm et al, 1998b).…”

Section: Secretory Featuresmentioning

confidence: 99%

Variations of concentric hair cells in a Cnidarian sensory epithelium (Coryne tubulosa)

Holtmann

Thurm

2001

J of Comparative Neurology

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In capitate hydropolyps, the spherical end-knobs of the short tentacles present an exceptional concentration of sensory functions in one of the evolutionarily oldest nervous systems. The tentacular spheres are the basis of sensation and discrimination of objects and of capturing of prey-objects by the discharge of nematocytes (stinging cells). Recent electrophysiological studies of the spheres revealed combined chemo/mechanosensory functioning of the nematocytes and mechanosensitivity of further types of cells. The present electron microscopical study made use of the small size of the spheres of Coryne tubulosa to characterize all cells of some spheres. Five types of ectodermal cells were found to have sensory structural features and to be separated by or enclosed in supporting cells: 1) nematocytes of the stenotele type; 2) short and 3) long ciliated concentric hair cells, which carry a cilium-stereovilli bundle, similar to the cnidocil apparatus of nematocytes; 4) cells having a recessed cilium-microvilli complex equipped with a thick cell-traversing rootlet (rootlet cells); and 5) cells having a recessed short cilium with no microvilli and only a short rootlet and containing, apically as well as basally, aggregations of dense-core vesicles (vesicle-rich cells). Types 1-4 vary the configuration of a concentric cilium-microvilli complex (variations of a concentric hair bundle) and were demonstrated or inferred to be mechanosensitive. Apical exocytotic activity, which is well known for the nematocytes (discharge of their cnidocyst), is indicated by ultrastructure for the nematocyte-resembling concentric hair cells and for the vesicle-rich cells. The tentacular spheres are considered an early paradigm of a sensory epithelium. Its synaptic structures and extensive connectivity are the subject of a subsequent paper.

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“…Clavidae (Morgenstern, 1901;Harm, 1903;van de Vyver, 1967), Hydractiniidae (van de Vyver, 1964de Vyver, , 1967Bodo & Bouillon, 1968;Weis et al, 1985;Weis & Buss, 1987), Corynidae (van de Vyver, 1967;Bodo & Bouillon, 1968), Halocordylidae (Hargitt, 1900;Martin & Thomas, 1977, 1980, 1981aHotchkiss et ai., 1984;Martin & Archer, 1986a, b), and Mitrocomidae (Martin et al, 1983). They indicate a mixture of both constant and variable developmental patterns between different families, revealing hydroid metamorphosis as a profitable field for comparative developmental studies.…”

Section: Introductionmentioning

confidence: 99%

Post-embryonic larval development and metamorphosis of the hydroidEudendrium racemosum (Cavolini) (Hydrozoa, Cnidaria)

Sommer

1990

Helgolander Meeresunters

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The morphology and histology of the planula larva of Eudendriurn racemosum (Cavolini)' and its metamorphosis into the primary polyp are described from light microscopic observations. The planula hatches as a differentiated gastrtfla. During the lecithotrophic larval period, large ectodermal mucous cells, embedded between epithellomuscular cells, secrete a sticky slime. Two granulated cell types occur in the ectoderm that are interpreted as secretory and sensorynervous cells, but might also be representatives of only one cell type with a multiple function. The entoderm consists of yolk-storing gastrodermal cells, digestive gland cells, interstitial cells, cnidoblasts, and premature cnidocytes. The larva starts metamorphosis by affixing its blunt aboral pole to a substratum. While the planula flattens down, the mucous cells penetrate the mesolamella and migrate through the entoderm into the gastral cavity where they are lysed. Subsequently, interstitial cells, cnidoblasts, and premature cnidocytes migrate in the opposite direction, i.e. from entoderm to ectoderm. Then, the polypoid body organization, comprising head (hydranth), stem and foot, all covered by pefidermal secretion, becomes recognisable. An oral constriction divides the hypostomal portion of the gastral cavity from the stomachic portion. Within the hypostomal entoderm, cells containing secretory granules differentiate. Following growth and the multiplication of tentacles, the head pefiderm disappears. A ring of gland cells differentiates at the hydranth's base. The positioning of cnidae in the tentacle ectoderm, penetration of the mouth opening and the multiplication of digestive gland cells enable the polyp to change from ledthotrophic to planktotrophic nutrition.

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BIOLOGY OF HYDRACTINIID HYDROIDS. 4. ULTRASTRUCTURE OF THE PLANULA OFHYDRACTINIA ECHINATA

Abstract: BIOLOGY OF HYDRACTINIID HYDROIDS. 4. ULTRASTRUCTURE OF THE PLANULA OF HYDR.4CTINIA ECHINATA

Cited by 52 publications

References 29 publications

Control of planula migration by LWamide and RFamide neuropeptides inHydractinia echinata

Control of planula migration by LWamide and RFamide neuropeptides inHydractinia echinata

Variations of concentric hair cells in a Cnidarian sensory epithelium (Coryne tubulosa)

Post-embryonic larval development and metamorphosis of the hydroidEudendrium racemosum (Cavolini) (Hydrozoa, Cnidaria)

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