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Spherical bodies present within the germinal vesicle of Podarcis sicula previtellogenic oocyte derive from the temporaneous inactivation of ribosomal genes
Author(s) -
Loredana Ricchiari,
Marina Prisco,
Stefania Tammaro,
Chiara Maria Motta,
Isabella Pugliese,
Piero Andreuccetti
Publication year - 2003
Publication title -
molecular reproduction and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.745
H-Index - 105
eISSN - 1098-2795
pISSN - 1040-452X
DOI - 10.1002/mrd.10028
Subject(s) - germinal vesicle , biology , oocyte , nucleolus , ribosomal rna , ultrastructure , microbiology and biotechnology , oogenesis , gene , genetics , anatomy , cytoplasm , embryo
In the present paper we have investigated the origin of the spherical bodies (SBs) present within the germinal vesicle of about 400 μm previtellogenic oocytes in the lizard Podarcis sicula . In particular, we have attempted to clarify whether they derive from the single, large nucleolus present in early diplotenic oocyte as a consequence of ribosomal gene inactivation. We have, therefore, experimentally induced a decrease in rRNA synthesis by injecting animals with D ‐galactosamine or by exposing them to low temperatures. The investigations carried out have demonstrated that both treatments induce significant ultrastructural changes in the nucleolar apparatus and in particular fragmentation and the formation of SBs comparable to those observed in germinal vesicle under physiological conditions. These results indicate that the germinal vesicle of Podarcis sicula has a nucleolar apparatus that significantly changes its aspect according to its functional status and reveal that in this species, the time course of rRNA synthesis is peculiar with respect to any other vertebrate oocyte studies so far. Mol. Reprod. Dev. 64: 321–328, 2003. © 2003 Wiley‐Liss, Inc.