An electron microscope study on the oocyte, test cells and follicular envelope of the tunicate, Molgula manhattensis

Kessel, Richard G.; Kemp, Norman E.

doi:10.1016/s0022-5320(62)90061-8

Cited by 51 publications

(18 citation statements)

References 28 publications

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“…These may be the precursor of the test cells of S. plicata, as they may be so for the follicular cells themselves. Neither definite nor acceptable view concerning their function was encountered, however, the review of Michael et al (2008) recorded that the test cells: (a) control the morphogenesis of the larval tunic (Cavey, 1976;Satoh et al, 1982;Cavey and Cloney, 1984); (b) nourish the oocyte (Kessel and Kemp, 1962); (c) provide the oocyte with yolk precursors (Mancuso, 1965); or (d) produce the pigment (Kessel, 1962). In S. plicata, the present work gives clear-cut histological evidence that they play a role in the process of vitellogenesis.…”

Section: Discussionmentioning

confidence: 99%

Studies on the reproductive and nervous systems of the protochordate Styela plicata (Lesueur, 1823) to correlate the nervous activity on reproduction

Bawab

Michael

Khalil

et al. 2012

Egyptian Journal of Aquatic Research

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Abu Kir Bay was found to be more suitable area for ascidian collection in Alexandria waters, especially the locality known, in public, the Dead Sea. Specimens of Styela plicata were collected monthly during 1 year. S. partita is usually found attached to the basal part of the other Styela. Both were carefully identified according to Vasseur (1967) andMillar (1970). Adult specimens of S. plicata with suitable and same size were dissected to examine both nervous and reproductive

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Section: Discussionmentioning

confidence: 99%

Studies on the reproductive and nervous systems of the protochordate Styela plicata (Lesueur, 1823) to correlate the nervous activity on reproduction

Bawab

Michael

Khalil

et al. 2012

Egyptian Journal of Aquatic Research

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“…Unequivocal experiments demonstrate that these enzymes are produced by the embryos (Osti 1950;Caggegi et al 1974). Many investigators have assumed that test cells nourish oocytes during oogenesis (Bancroft 1899;Harvey 1927;Tucker 1942;Kessel & Kemp 1962;Mancuso 1965;Gianguzza & Dolcemascolo 1979;Kessel 1983) or transport pigment into oocytes (Eissa & Salem 1992), but there is no experimental or ultrastructural evidence to support these hypotheses, and the function of the test cells is still unknown.…”

Section: Introductionmentioning

confidence: 99%

Ascidian Larvae: The Role of Test Cells in Preventing Hydrophobicity

Cloney

Hansson

1996

Acta Zoologica

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Cloney, R. A. & Hansson, L. J. 1996. Ascidian larvae: the role of test cells in preventing hydrophobicity.-Acra Zoologica (Stockholm) 77: 73-78.Ascidian test cells co-differentiate on the surface of each ovarian oocyte beneath the vitelline coat. They become vacuolated and later occupy the perivitelline Compartment of each egg and embryo. In some species, their vacuoles contain submicroscopic granules or filaments called 'ornaments' and acidic glycosaminoglycans. These test cells deposit their products on the surface of the larval tunic in late embryogenesis. In these species, the test cells are lost at hatching. In other species, the test cell vacuoles contain acidic glycosaminoglycans, but no ornaments. In these species, the test cells attach to the larval tunic and probably secrete acidic glycosaminoglycans. We deprived the embryos of seven species of ascidians of their test cells and vitelline coats during midembryogenesis. After completing their development, the larvae of both kinds of species were hydrophobic. They easily become trapped on the surface of sea water in cultures. Normal larvae (controls), bearing test cell secretions, are hydrophilic and never become trapped. We infer that negatively charged secretions of the test cells make normal larvae hydrophilic. Some molgulids with direct development have no test cells, no fins and no swimming larva. We reason that the test cells of these species may have been lost during evolution because they no longer had an important role in preventing hydrophobicity.

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“…Ever since test cells were first discovered some 100 years ago, their function has remained unclear. They have notably been ascribed a role in nutrition of the oocyte during vitellogenesis (P6rez, 1954;Kessel & Kemp, 1962;Mancuso, 1965;Reverberi, 1978) or being involved in tunic morphogenesis (Cloney & Cavey, 1982). In Distaplia occidentalis (Cavey, 1976) and Corella mflata (Cloney & Cavey, 1982), they form minute ornaments, which cover the larval tunic.…”

Section: Introductionmentioning

confidence: 99%

Do test cells secrete a hatching enzyme inAscidiella aspersa (Tunicata, Ascidiacea)?

Lübbering

Hofmann

1995

Helgolander Meeresunters

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An electron microscope study on the oocyte, test cells and follicular envelope of the tunicate, Molgula manhattensis

Cited by 51 publications

References 28 publications

Studies on the reproductive and nervous systems of the protochordate Styela plicata (Lesueur, 1823) to correlate the nervous activity on reproduction

Studies on the reproductive and nervous systems of the protochordate Styela plicata (Lesueur, 1823) to correlate the nervous activity on reproduction

Ascidian Larvae: The Role of Test Cells in Preventing Hydrophobicity

Do test cells secrete a hatching enzyme inAscidiella aspersa (Tunicata, Ascidiacea)?

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