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Dynamics and cytochemistry of oogenesis in Leporinus striatus Kner (Teleostei, Characiformes, Anostomidae) from the Rio Sapucaí, Minas Gerais State, Brazil

Abstract

Oogenesis involves a sequense of transformations which are undergone by female germ cells. These cells change into oogonias and then into mature oocytes. Sexually mature females were collected monthly, during one year, from the Rio Sapucaí, tributary of the Rio Grande, which is part of the Furnas Reservoir system in the state of Minas Gerais. The observed material showed that oogonias were small spherical cells, had a big spherical nucleus, with a single nucleolus, and weakly stained cytoplasm with eosinophilic granules (FG stained), which indicate their protein content. The primary oocytes showed a big basophilic nucleus, with a large peripheral nucleolus, and several smaller nucleoli. They show a reduced cytoplasmic content. The previtellogenic oocytes presented voluminous cytoplasm and nucleus with several small peripheral nucleoli. The oocytes underwent vitellogenesis with the development of the zona radiata and the follicle cells. The zona radiata had two layers, the outer and the inner, which showed its protein content when stained with CM and FG techniques. TB pH 2.5 and pH 4.0 staining showed that oocytes undergoing vitellogenesis presented weakly stained cytoplasm and peripheral cytoplasmic vesicles. The follicle cells that were squamous became cuboidal. In mature oocytes, the yolk granules that filled the cytoplasm became green and blue when stained with FG and CM techniques, indicating their protein content. The perivitclline region showed rosy stained vesicles (TB pH 2.5 and pH 4.0) spread among the weakly stained peripheral vesicles, which seemed to be the cortical alveoli. The zona radiata cells, CM and FG stained, still showed two layers like the oocytes from the previous stage, but thicker.

Teleostei; Anostomidae; Leporinus striatus; oogenesis; cytochemical


Dynamics and cytochemistry of oogenesis in Leporinus striatus Kner (Teleostei, Characiformes, Anostomidae) from the Rio Sapucaí, Minas Gerais State, Brazil

Helena A.S. ChiniI; José Antônio Dias GarciaII; Edson Luis MaistroIII; Irani Quagio-GrassiottoIV

IInstituto de Odontologia e Ciências da Saúde, UNIFENAS. Caixa Postal 23, 37130-000 Alfenas, Minas Gerais, Brasil

IIFaculdade de Medicina Veterinária, Departamento de Medicina Veterinária Preventiva, UNIFENAS. Caixa Postal 23, 37130-000 Alfenas, Minas Gerais, Brasil

IIIInstituto de Farmácia e Nutrição, UNIFENAS. Caixa Postal 23, 37130-000 Alfenas, Minas Gerais, Brasil. Brasil. E-mail: maistro.edson@unifenas.br

IVDepartamento de Morfologia, Instituto de Biociências, Universidade Estadual Paulista. Campus Rubião Júnior, 18300-000 Botucatu, São Paulo, Brasil

ABSTRACT

Oogenesis involves a sequense of transformations which are undergone by female germ cells. These cells change into oogonias and then into mature oocytes. Sexually mature females were collected monthly, during one year, from the Rio Sapucaí, tributary of the Rio Grande, which is part of the Furnas Reservoir system in the state of Minas Gerais. The observed material showed that oogonias were small spherical cells, had a big spherical nucleus, with a single nucleolus, and weakly stained cytoplasm with eosinophilic granules (FG stained), which indicate their protein content. The primary oocytes showed a big basophilic nucleus, with a large peripheral nucleolus, and several smaller nucleoli. They show a reduced cytoplasmic content. The previtellogenic oocytes presented voluminous cytoplasm and nucleus with several small peripheral nucleoli. The oocytes underwent vitellogenesis with the development of the zona radiata and the follicle cells. The zona radiata had two layers, the outer and the inner, which showed its protein content when stained with CM and FG techniques. TB pH 2.5 and pH 4.0 staining showed that oocytes undergoing vitellogenesis presented weakly stained cytoplasm and peripheral cytoplasmic vesicles. The follicle cells that were squamous became cuboidal. In mature oocytes, the yolk granules that filled the cytoplasm became green and blue when stained with FG and CM techniques, indicating their protein content. The perivitclline region showed rosy stained vesicles (TB pH 2.5 and pH 4.0) spread among the weakly stained peripheral vesicles, which seemed to be the cortical alveoli. The zona radiata cells, CM and FG stained, still showed two layers like the oocytes from the previous stage, but thicker.

Key words: Teleostei, Anostomidae, Leporinus striatus, oogenesis, cytochemical

Full text available only in PDF format.

ACKNOWLEDGEMENTS. The authors are grateful to Mr. Antônio Vicente Salvador and Mr. Ricardo André dos Santos for the technical help, and to Dr. Francisco Langeani Filho for identifying the specimens. Funds supporting this study were provided by FAPEMIG. Hidroelétrica de Furnas and UNIFENAS.

Recebido em 31.VIII.2000; aceito em 15.X.2001.

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Publication Dates

  • Publication in this collection
    03 June 2009
  • Date of issue
    Dec 2001

History

  • Accepted
    15 Oct 2001
  • Received
    31 Aug 2000
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