Histochemical characterisation of oocytes of the swordfish Xiphias gladius | Caracterización histoquímica de ovocitos de pez espada, Xiphias Gladius

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[EN] This paper reports a histological, histochemical and immunohistochemical characterisation of growing oocytes of the swordfish Xiphias gladius. The presence and distribution of carbohydrates, proteins, lipids, calcium, iron, vitellogenin/Vg, zona radiata protein/Zrp, metallothionein/Mt, and thyroid hormones/T3-T4 were studied during oogenesis (cortical alveoli, globules, yolk-granules, cytoplasm, follicular and radiata envelopes). During the initial vitellogenic phase, the oocytes showed cortical alveoli and oil globules containing neutral lipids exclusively. During this phase, small yolk granules appeared around the peripheral cytoplasm, and they increased through exogenous vitellogenesis. Yolk granules were composed of glycoproteins, calcium, iron, and proteins rich in lysine, arginine, tyrosine, tryptophan, cysteine and cystine. Vg and Mt were immunohistochemically detected in yolk. The follicular envelope contained proteins rich in amino acids. Moreover, calcium and thyroid hormones (triiodotyronine and thyroxine/T3, T4) were detected in this cell envelope. Cortical alveoli, which contained carboxylated and neutral glycoconjugates, were especially rich in N-acetyl-D-galactosamine, N-acetyl-D-glucosamine, galactose and sialic acid. Finally, the zona radiata was mainly proteinaceous in nature and was composed of calcium and neutral glycoproteins. The egg envelope or chorion and the liver showed specific immunoreactivities by using anti-salmon Zrp as the primary antiserum

[ES] En este trabajo se realiza una caracterización histológica, histoquímica e inmunohistoquímica de los ovocitos en crecimiento del pez espada, Xiphias gladius. Se estudia la presencia y distribución de carbohidratos, proteínas, lípidos, calcio, hierro, vitelogenina/Vg, proteína radiada/Zrp, metalotioneina/Mt y hormonas tiroideas/ T3-T4 durante la ovogénesis (alveolos corticales, glóbulos, gránulosvitelo, citoplasma, capas folicular y radiada). Durante la fase inicial de la vitelogénesis, los ovocitos presentan alveolos corticales y una gota lipídica conteniendo exclusivamente lípidos neutros. Durante esta fase en la periferia del citoplasma aparecen pequeños granulos de vitelo, incrementando progresivamente durante la vitelogénesis exógena. Los gránulos de vitelo están compuestos por glicoproteínas, calcio, hierro, proteínas ricas en lisina, arginina, tirosina, triptófano, cisteina y cistina, y contienen Vg y Mt. La capa folicular de los ovocitos del pez espada está compuesta por glicoproteínas y proteínas ricas en diferentes aminoácidos. Esta envuelta contiene calcio y hormonas tiroideas/ T3 y T4. Los alveolos corticales están constituidos por glicoconjugados carboxilados y neutros, y son especialmente ricos en N-acetil-D-galactosamina, N-acetil- D-glucosamina, galactosa y ácido siálico. Finalmente, la capa radiada, fundamentalmente proteica, contiene calcio y glicoproteínas neutras. Utilizando anti-salmon Zrp, como anticuerpo primario, el corion o capa radiada y el hígado muestran una immunoreactividad específica.

This work was partially funded by ICMAN.CSIC and the Spanish projects (MCYT/AGL2005-02478 and AGL2006-13777- CO3-O2/ACU). J.B. Ortiz-Delgado is supported by the Programa Ramón y Cajal (MEC, Spain).

Peer reviewed