Loss of test cells leads to the formation of new tunic surface cells and abnormal metamorphosis in larvae of Ciona intestinalis (Chordata, Ascidiacea) |
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Authors: | Y Sato Masaaki Morisawa |
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Institution: | (1) Misaki Marine Biological Station, Graduate School of Science, University of Tokyo, Koajiro, Misaki, Miura, Kanagawa, 238-0225, Japan Tel.: +81-468-814105 Fax: +81-468-817944, JP |
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Abstract: | The larvae of the ascidian Ciona intestinalis from which the chorion with the test cells and follicle cells were removed developed normally without the test cells until
the early tailbud stage. A number of round-shaped cells morphologically similar to the test cells but with different lectin
affinities and autofluorescence, then appeared on the neck region of the demembranated embryos. The new cells had three different
types: round, particulate, and granular, and these cells increased in number after the late tailbud stage. The morphology
of the adhesive papillae, tunic layers and epidermis of the demembranated larvae was similar to that of control larvae; however,
the affinity to lectins was different in the swimming period. Control larvae attached to the substratum after the swimming
period, resorbed the tail completely and underwent rotation of the visceral organs. Conversely, rotation occurred before completion
of tail resorption in the demembranated larvae. Furthermore, the metamorphic events progressed more slowly in the demembranated
larvae. These results suggest that the test cells play important roles in normal development and morphogenesis of ascidian
larvae.
Received: 4 December 1998 / Accepted: 9 April 1999 |
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Keywords: | Test cell Demembranated larva Metamorphosis Lectin Ascidian |
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