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Structural and ultrastructural analysis of embryonic development of Prochilodus lineatus (Valenciennes, 1836) (Characiforme; Prochilodontidae)

Published online by Cambridge University Press:  01 August 2006

Alexandre Ninhaus-Silveira*
Affiliation:
Universidade Estadual Paulista (UNESP), Depto. de Biologia e Zootecnia, Ilha Solteira, São Paulo, Brazil.
Fausto Foresti
Affiliation:
Universidade Estadual Paulista (UNESP), Depto. de Morfologia, Botucatu, São Paulo, Brazil.
Alexandre de Azevedo
Affiliation:
Universidade Estadual Paulista (UNESP), Depto. de Morfologia, Botucatu, São Paulo, Brazil.
*
All correspondence to: A. Ninhaus-Silveira, Departamento de Biologia e Zootecnia, Universidade Estadual Paulista/Ilha Solteira, Av. Brasil, 56, Centro, Postal Box 31, CEP: 15385-000, Ilha Solteira, São Paulo, Brazil. Tel/Fax: +55 02118 3743-1285/3743-1186. e-mail: ninhaus@bio.feis.unesp.br

Summary

This survey was performed to characterize the embryogenesis of Prochilodus lineatus. Seven stages of embryo development were identified – zygote, cleavage, blastula, gastrula, segmentation, larval and hatching – after a period of incubation of 22 h (24 °C) or 14 h (28 °C). The following cleavage pattern was identified: the first plane was vertical (2 blastomeres); the second was vertical and perpendicular to the first (4 blastomeres); the third was vertical and parallel to the first (4 × 2); the fourth cleavage was vertical and parallel to the second (4 × 4); the fifth was vertical and parallel to the first (4 × 8); and the sixth cleavage was horizontal (64 blastomeres). At the blastula stage (3.0–4.0 h (24 °C); 1.66–2.0 h (28 °C)) irregular spaces were detected and periblast structuring was initiated. At the gastrula stage (4.0–8.0 h (24 °C); 3.0–6.0 h (28 °C)) the epiboly, convergence and cell movements, as well as the formation of embryonic layers, had begun. The segmentation stage (10.0–15.0 h (24 °C); 7.0–10.0 h (28 °C)) was characterized by a rudimentary formation of organs and systems (somites, optic vesicle and intestinal delimitation). The embryo at the larval stage (16.0–21.0 h (24 °C); 11.0–13.0 h (28 °C)) showed a free tail, more than 25 somites, an optic vesicle and a ready-to-hatch larval shape. The blastomeres at cleavage stage had disorganized nuclei indicating high mitotic activity. At gastrula, the blastomeres and the periblast had euchromatic nuclei and a large number of mitochondria and vesicles. The yolk was organized into globose sacs, which were dispersed into small pieces prior to absorption.

Information

Type
Research Article
Copyright
Copyright © Cambridge University Press 2006

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