Organization and characterization of the keratin cytoskeleton in the previtellogenic ovarian follicle of the lizardPodarcis sicula Raf

Maurizii, Maria Gabriella; Alibardi, Lorenzo; Taddei, Carlo

doi:10.1002/1098-2795(200010)57:2<159::aid-mrd7>3.0.co;2-n

Cited by 12 publications

(5 citation statements)

References 22 publications

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“…The observations on the centres of nucleation (centrosomes) of this extensive microtubule network, carried out by immunolabeling of γ‐tubulin, were addressed to the growing germ cell and to the somatic follicle cells which surround the oocyte. Regarding the growing oocytes, we showed that in the prediplotenic stages of this reptilian sauropsid a degeneration of the centrosomes occurs and the γ‐tubulin turns out to be dispersed inside the oocyte cytoplasm as reported in the oogenesis of both invertebrates and vertebrates (Manandhar et al,2005). In the larger oocytes, surrounded by a mono‐layered follicular epithelium, the immunolabeling of the γ‐tubulin is strong and homogenously dispersed.…”

Section: Discussionsupporting

confidence: 67%

Microtubule organization and nucleation in the differentiating ovarian follicle of the lizard Podarcis sicula

Maurizii¹,

Taddei²

2012

Journal of Morphology

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We analyzed the organization of the microtubular cytoskeleton and the distribution of centrosomes at the different stages of differentiation of the ovarian follicle of the lizard Podarcis sicula by examining immunolabeled α- and γ-tubulins using confocal microscopy. We observed that in the follicular epithelium the differentiation of the nurse pyriform cells is accompanied by a reorganization of the microtubules in the oocyte cortex, changing from a reticular to a radial pattern. Furthermore, these cortical microtubules extend in the cytoplasm of the connected follicle cells through intercellular bridges. Radially oriented microtubules were still more marked in the oocyte cortex during the final stages of oogenesis, when the yolk proteins were incorporated by endocytosis. The nucleation centres of the microtubules (centrosomes) were clearly detectable as γ-tubulin immunolabeled spots in the somatic stromal cells of the germinal bed. A diffuse cytoplasmic immunolabeling together with multiple labeled foci, resembling the desegregation of the centrosomes in early oogenesis of vertebrates and invertebrates, was revealed in the prediplotenic germ cells. In the cytoplasm of growing oocytes, a diffuse labeling of the γ-tubulin antibody was always detectable. In the growing ovarian follicles, immunolabeled spots were detected in the mono-layered follicle cells which surrounded the early oocytes. In follicles with a polymorphic follicular epithelium, only the small follicle cells showed labeled spots. A weak and diffuse labeling was observed in the pyriform cells while in the enlarging intermediate cells the centrosomes degenerated like in the early oocytes. Our observations confirm that in P. sicula most of the oocyte growth is supported by the structural and functional integration of the developing oocyte with the pyriform nurse cells and suggest that their fusion with the oocyte results in an acquirement by these somatic cells of characteristics typical of the germ cells.

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Section: Discussionsupporting

confidence: 67%

Microtubule organization and nucleation in the differentiating ovarian follicle of the lizard Podarcis sicula

Maurizii¹,

Taddei²

2012

Journal of Morphology

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“…However, unlike nurse cells that are germline in origin, pyriform cells differentiate from small somatic follicle cells after their fusion with the oocyte (Andreuccetti et al 1978), and the intermediate cells represent the initial step in this differentiation (Filosa et al 1979). Using immunostaining and light microscopy, we reported the presence of a cytokeratin network in the cytoplasm of pyriform cells which crosses their apex and extends through the intercellular bridges and into the oocyte cortex (Maurizii et al 2000). We have also reported that the tubulin cytoskeleton is involved in the interaction between the somatic follicle cells and the growing oocyte (Maurizii et al 2004).…”

Section: Introductionmentioning

confidence: 93%

Vasa protein is localized in the germ cells and in the oocyte-associated pyriform follicle cells during early oogenesis in the lizard Podarcis sicula

et al. 2009

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The vasa gene, first identified in Drosophila, is a key determinant for germline formation in eukaryotes. Homologs of vasa have been identified and linked to germline development, in many invertebrates and vertebrates. Here, we analyze the distribution of Vasa in early germ cells (oogonia and oocytes) and previtellogenic ovarian follicles of the lizard Podarcis sicula. During most of its previtellogenic growth, the oocyte in this lizard species is structurally and functionally integrated through intercellular bridges with special follicle cells called pyriform cells. The pyriform cells function similarly to Drosophila nurse cells, but are somatic in origin. In the oogenesis of P. sicula, Vasa is initially highly detected in the oogonia, but its levels decrease in early stage oocytes before the onset of pyriform cell differentiation. In the later stages of oogenesis, the high level of Vasa is related with the nurse function of the pyriform follicle cells. These observations suggest that cells of somatic origin are engaged in the synthesis of Vasa in the oogenesis of this lizard.

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“…By contrast, in vitellogenic follicles, when the follicular epithelium is constituted only by small cells, immunostain is evident at the level of the oocyte cortex and the cytoplasm of regressing pyriform cells. The present data strongly suggest that the α and β spectrin pattern put in evidence during the different phases of lizard oocyte growth is related to the differentiation of small into pyriform cells, where such protein may guarantee a relationship between surface glycoproteins (Andreuccetti et al, 2001: Anat Rec 263:1–9), and the cytoskeleton distribution (Maurizii et al, 2000: Raf Mol Reprod Dev 57:159–166). Furthermore, the distribution of spectrin mRNA, similar to that observed for the protein, demonstrates that spectrin, once synthesized within pyriform cells, is transferred through intercellular bridges in the oocyte cortex, thus confirming that pyriform cells are nurse that significantly are involved in the oocyte growth.…”

mentioning

confidence: 51%

α and β spectrin distribution during the differentiation of pyriform cells in follicles of lizard Podarcis sicula

Ricchiari

Vaccaro

Prisco

et al. 2003

Molecular Reproduction Devel

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Using alpha and beta spectrin mammalian antibodies on Western blotting, we demonstrated that lizard ovarian follicles contain two isoforms of alpha spectrin, Mr 94 and 134 kDa, and a 230 kDa beta spectrin, and that their pattern modifies in relation to pyriform cell differentiation. In fact, a positive immunoreaction is firstly evident within follicular epithelium of previtellogenic follicles when small cells differentiate into pyriform cells via intermediate cells. Later on, immunostain is present in pyriform cells and in the oocyte cortex that previously appears unstained. It is noteworthy that immunostain is also present on small cells located in contact with the oocyte membrane, but not on those located under the basal lamina and among pyriform cells, not engaged in pyriform cell differentiation. During the subsequent stages of previtellogenic phase, spectrin immunostain over the follicular epithelium and in the oocyte cortex does not change. By contrast, in vitellogenic follicles, when the follicular epithelium is constituted only by small cells, immunostain is evident at the level of the oocyte cortex and the cytoplasm of regressing pyriform cells. The present data strongly suggest that the alpha and beta spectrin pattern put in evidence during the different phases of lizard oocyte growth is related to the differentiation of small into pyriform cells, where such protein may guarantee a relationship between surface glycoproteins (Andreuccetti et al., 2001: Anat Rec 263:1-9), and the cytoskeleton distribution (Maurizii et al., 2000: Raf Mol Reprod Dev 57:159-166). Furthermore, the distribution of spectrin mRNA, similar to that observed for the protein, demonstrates that spectrin, once synthesized within pyriform cells, is transferred through intercellular bridges in the oocyte cortex, thus confirming that pyriform cells are nurse that significantly are involved in the oocyte growth. Finally, the present data demonstrate that alpha spectrin of lizard ovarian follicles has Mr quite different from those so far reported and may constitute a new group of isoforms. This important result will be the focus of future experiments. Mol. Reprod. Dev. 67: 101-107, 2004.

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Organization and characterization of the keratin cytoskeleton in the previtellogenic ovarian follicle of the lizardPodarcis sicula Raf

Cited by 12 publications

References 22 publications

Microtubule organization and nucleation in the differentiating ovarian follicle of the lizard Podarcis sicula

Microtubule organization and nucleation in the differentiating ovarian follicle of the lizard Podarcis sicula

Vasa protein is localized in the germ cells and in the oocyte-associated pyriform follicle cells during early oogenesis in the lizard Podarcis sicula

α and β spectrin distribution during the differentiation of pyriform cells in follicles of lizard Podarcis sicula

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