Cnidarian Histology

Chapman, David M. F.

doi:10.1016/b978-0-12-512150-7.50006-2

Cited by 64 publications

(60 citation statements)

References 93 publications

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“…A weak argument is that the ectoderm in the oral disc differs from that of the body column (and that of the basal disc). For instance, the musculature differs (Chapman 1974(Chapman , 1999Hentschel and Hündgen 1980;Pollmanns and Hündgen 1981;Matsuno 1983). Further, the subumbrella of the first ephyra formed in strobilation ranges exactly from the polyp's mouth to the polyp's ring of tentacles.…”

mentioning

confidence: 99%

Compartments in Scyphozoa

Berking

Herrmann²

2007

Int. J. Dev. Biol.

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Polyps of Scyphozoa have a cup-shaped body. At one end is the mouth opening surrounded by tentacles, at the other end is an attachment disc. The body wall consists of two tissue layers, the ectoderm and the endoderm, which are separated by an extracellular matrix, the mesoglea. The polyp's gastric cavity is subdivided by septa running from the apical end to the basal body end. The septa consist of two layers of endoderm and according to biology textbooks the number of septa is four. However, in rare circumstances Aurelia produces polyps with zero, two, six, or eight septa. We found that the number was always even. Therefore we propose that two types of endoderm exist, forming alternating stripes running from the oral body end to the aboral end. The stripes have some properties of developmental compartments. Where cells of different compartments meet, they form a septum. We also propose that the ectoderm is subdivided into compartments. The borders of the ectodermal and endodermal compartments are perpendicular to each other. Tentacles of the polyp and rhopalia (sense organs) of the ephyra (young medusa), respectively, develop at the border between two ectodermal compartments. The number can be even or odd. Rhopalia formation is particularly favored where two ectodermal and two endodermal compartments meet.

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mentioning

confidence: 99%

Compartments in Scyphozoa

Berking

Herrmann²

2007

Int. J. Dev. Biol.

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“…Amoebocytes, mainly in the mesoglea, serve as the stem cells (reviewed in Robson 1957, Chapman 1974, Young 1974, Larkman 1981, Fadlallah 1983) Since Scyphozoa and Anthozoa lack the extensive regenerative powers of the Hydrozoa with deflned interstitial cells (reviewed in Young 1974), cases of regenera.tion in hydroz0an.s will not be discussed here.…”

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confidence: 99%

Do reproduction and regeneration in damaged corals compete for energy allocation?

Rinkevich¹

1996

Mar. Ecol. Prog. Ser.

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Several field studles have revealed that damaged corals have lower fecundity during regeneration as compared to intact colonies. Thls finding was ~nterpreted as suggesting that there is a trade-off in the allocation of energy between reproductive activities versus growth and regeneration in corals, where sexual reproduction is easily disrupted. However, 3 independent lines of evidence critically challenge the paradigm of energy allocation trade-off and suggest that (1) sexual reproduction in cnidarians may not always be subject to energy constraints and may possess a hierarchial function, (2) shallow-water scleractinians may not be prone to energy constraints, and (3) regeneration is a regulated process expressed through programmed events and not directly related to the energy trade-off principle Growth, tissue repair and the production of the germ cell require 1 major resource, the stem cells It is suggested that any extensive use of these reserve cells may reduce their numbers and significantly affect one or more biological functions. Several studies indirectly confirm this idea. Trade-offs for stem cells between tissue repair and sexual reproduction should be considered as a relevant factor shaping reproduct~ve activities during regeneration in reef corals.

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“…Positioning of the cells. Each I-group cell perforates a supporting cell and remains inserted within this cell, as has already been reported for concentric hair cells outside the tentacular spheres (Tardent and Schmid, 1972); this is the general fashion of insertion of nematocytes in Hydra (Chapman, 1974). E-group cells are located between the supporting cells, as is usual in sensory epithelia of higher phyla.…”

Section: Classifying the Sensory Cellsmentioning

confidence: 81%

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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Cnidarian Histology

Cited by 64 publications

References 93 publications

Compartments in Scyphozoa

Compartments in Scyphozoa

Do reproduction and regeneration in damaged corals compete for energy allocation?

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

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