Proceedings of the 5th International Symposium on EQUINE ...
Proceedings of the 5th International Symposium on EQUINE ...
Proceedings of the 5th International Symposium on EQUINE ...
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Havemeyer Foundati<strong>on</strong> M<strong>on</strong>ograph Series No. 3equine oocytes matured in vitro (Table 1).However, <str<strong>on</strong>g>the</str<strong>on</strong>g> number <str<strong>on</strong>g>of</str<strong>on</strong>g> oocytes that reachedmetaphase II (MII) in vitro was not different whenFCS, PVA and fetuin was added to <str<strong>on</strong>g>the</str<strong>on</strong>g> medium(Table 1). This is in agreement with our previousresults showing similar maturati<strong>on</strong> rates for equineoocytes matured in presence or absence <str<strong>on</strong>g>of</str<strong>on</strong>g> serumand horm<strong>on</strong>es (Landim-Alvarenga and Choi1999).In this experiment <str<strong>on</strong>g>the</str<strong>on</strong>g> time necessary fordigesti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> 50% <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> z<strong>on</strong>a pellucida (d 50 ) justafter collecti<strong>on</strong> was 12.04 min. There was nochange in ZP hardening during <str<strong>on</strong>g>the</str<strong>on</strong>g> culture periodwhen PVA was used. When FCS and Fetuin wereadded to <str<strong>on</strong>g>the</str<strong>on</strong>g> maturati<strong>on</strong> media <str<strong>on</strong>g>the</str<strong>on</strong>g> time necessaryfor digesti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> 50% <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> z<strong>on</strong>a (d 50 ) decreased inl<strong>on</strong>ger periods <str<strong>on</strong>g>of</str<strong>on</strong>g> culture, however no statisticdifference were noted (Table 2). After 36 h <str<strong>on</strong>g>of</str<strong>on</strong>g>maturati<strong>on</strong> <str<strong>on</strong>g>the</str<strong>on</strong>g> d 50 <str<strong>on</strong>g>of</str<strong>on</strong>g> equine oocytes matured inpresence <str<strong>on</strong>g>of</str<strong>on</strong>g> FCS and fetuin was lower comparedwith <str<strong>on</strong>g>the</str<strong>on</strong>g> group with PVA (Table 2). This is inagreement with <str<strong>on</strong>g>the</str<strong>on</strong>g> results <str<strong>on</strong>g>of</str<strong>on</strong>g> Schroeder et al.(1990) who showed that fetuin inhibited z<strong>on</strong>apellucida hardening <str<strong>on</strong>g>of</str<strong>on</strong>g> mouse oocytes in a dosedependent way. Also Dell’ Aquila et al. (1998)observed that bovine fetuin inhibited z<strong>on</strong>apellucida hardening <str<strong>on</strong>g>of</str<strong>on</strong>g> equine oocytes during IVMwith a dose effect.Oocyte maturati<strong>on</strong> in vitro or in vivo isaccompanied by a slow release <str<strong>on</strong>g>of</str<strong>on</strong>g> approximately30–40% <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> cortical granules (Dulcibella et al.1990). However, in vivo, this precocious release<str<strong>on</strong>g>of</str<strong>on</strong>g> cortical granules does not result in z<strong>on</strong>apellucida modificati<strong>on</strong>s. In fact, <str<strong>on</strong>g>the</str<strong>on</strong>g> d 50 measuredin 12 in vivo matured oocytes aspirated frompreovulatory follicles 30 h after hCG injecti<strong>on</strong>was 9.22 min.The ultrastructural analysis <str<strong>on</strong>g>of</str<strong>on</strong>g> in vivo maturedoocytes showed <str<strong>on</strong>g>the</str<strong>on</strong>g> highest number <str<strong>on</strong>g>of</str<strong>on</strong>g> CC beneath<str<strong>on</strong>g>the</str<strong>on</strong>g> oolema. Similar pattern was observed whenoocytes were matured in vitro for 36 h in presence<str<strong>on</strong>g>of</str<strong>on</strong>g> Fetuin and FCS. However, when maturati<strong>on</strong>occurs in absence <str<strong>on</strong>g>of</str<strong>on</strong>g> serum, <str<strong>on</strong>g>the</str<strong>on</strong>g> number <str<strong>on</strong>g>of</str<strong>on</strong>g> CC wassmaller. These indicate that in this group aprecocious release <str<strong>on</strong>g>of</str<strong>on</strong>g> CG may happened,justifying <str<strong>on</strong>g>the</str<strong>on</strong>g> high d 50 value observed.We c<strong>on</strong>clude that equine ZP became resistantto lisys by protease following 36 h incubati<strong>on</strong> inserum free media. The additi<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> fetuin or FCS to<str<strong>on</strong>g>the</str<strong>on</strong>g> maturati<strong>on</strong> media reduced <str<strong>on</strong>g>the</str<strong>on</strong>g> d 50 to valuessimilar to <str<strong>on</strong>g>the</str<strong>on</strong>g> <strong>on</strong>es observed in vivo maturedoocytes. It is likely that <str<strong>on</strong>g>the</str<strong>on</strong>g> problems related toIVF <str<strong>on</strong>g>of</str<strong>on</strong>g> equine oocytes matured in presence <str<strong>on</strong>g>of</str<strong>on</strong>g>serum are not related with ZPH.ACKNOWLEDGEMENTSSupported by PEG - CSU/USA, FAPESP/Braziland FUNDUNESP/ Brazil.REFERENCESChoi, Y.H., Hochi, S., Braun, J. and Oguri, N. (1993)Theriogenol. 40, 959-66.Dell’Aquila, M.E., De Felici, M., Maritato, F.,Lacalandra, G.M. and Minoia, P. (1998) In:<str<strong>on</strong>g>Proceedings</str<strong>on</strong>g> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g> 14th Scientific Meeting <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>the</str<strong>on</strong>g>European Society <str<strong>on</strong>g>of</str<strong>on</strong>g> Embryo Transfer, Venice, Italy.Abstract. 140.Dell’Aquila, M.E., Felici, M., Massari, S., Maritato, F.and Minoia, P. (1999) Biol. Reprod. 61, 533-540.Doulcibella, T., Kurasawa, S., Rangarjn, S., Kopf, G.S.and Schultz, R.M. (1990) Dev. Biol. 137, 46-55.Landim-Alvarenga, F.C. and Choi, Y.H. (1999)Theriogenol. 51, 383.Schroeder, A.C., Schultz, R.M., Kopf, G.S., Taylor, F.R.,Becker, R.B. and Eppig, J.J. (1990) Biol. Reprod. 43,891-897.Zhang, X., Rutlege, J. and Armstr<strong>on</strong>g, D.T. (1991) Mol.Reprod. Dev. 28, 292-6.27