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Histological characterization of cellular types during Scinax fuscovarius oogenesis (Lutz) (Anura, Hylidae)

DOI: 10.1590/S0101-81752004000400029

Keywords: oocytes, oogonia, ovary, pigment, vitellogenesis.

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this paper describes morphological characteristics of the ovarian germinative cells of the scinax fuscovarius (lutz, 1925). the ovary is organized in primordial germinative cells (oogonia) and follicular structures (ovarian follicle) - oocytes surrounded by follicular cells. oogonia: their nests are peripherically localized, containing cells with large and oval nucleus. oocytes i: basophilic cytoplasm; the spherical nucleus presents few nucleoli, one or two; the follicular cells (one tenuous layer) surround these previtellogenic cells. oocytes ii: the cell is larger and the cytoplasm becomes more basophilic; the nucleus presents few nucleoli and contains many chromosomes in the periphery (beginning the perinucleolar stage). oocytes iii: the cytoplasm acquires an intense acidophilia; the peripherical region of cytoplasm is filled with yolk and the internal region has no yolk at all; pigment synthesis begins; the follicular envelope presents three tenuous layers: an inner acellular (vitelline envelope) and two cellular layers (follicle cells). oocytes iv: a characteristic of this stage is the differentiation between the animal and the vegetal poles; the nucleus in the animal hemisphere and the pigments give the oocyte a color dark brown; the vitellogenesis is intense and the yolk occupies the whole cytoplasm.


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