Abstract
We investigated the occurrence and ultrastructurally characterized electrondense nuclear material (nuage) released from the nucleus during oogenesis and early spermatogenesis of Piaractus mesopotamicus, a fish from Pantanal Matogrossense (Brazil) having a seasonal reproductive cycle. The female germ cells presented two instances of nuclear material extrusion: in the oogonia and in the oocyte in the perinucleolar phase. In males, material with similar morphology and behavior occurred in the spematogonia. In all cases, this material was associated to mitochondria. The possible function of this material is discussed.
Highlights
As do most vertebrates, suspend meiosis in diplotene (prophase of the first meiosis division) until ovulation
Female fish, as do most vertebrates, suspend meiosis in diplotene until ovulation
In the testes and ovaries of this species of fish, as in others, oogonia and spermatogonia are found alone, or in groups of two or three in the follicle wall (Dadzie, 1969; Shrestha & Khanna, 1978; Grier, 1981; Romagosa, 1991; Romagosa et al, 1993, 2000). These germ cells usually were large with the nucleus occupying a considerable part of their volume, presenting in the cytoplasm many spherical mitochondria and very few endoplasmic reticulum profiles (Figs. 1A and 2A, B)
Summary
As do most vertebrates, suspend meiosis in diplotene (prophase of the first meiosis division) until ovulation. In the primary growth stage, material is frequently found in the oocytes, similar to that of the nucleoli in the outer face of the nuclear envelope.
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