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Ultrastructural localisation of calcium deposits in pig oocytes maturing in vitro: effects of verapamil

Published online by Cambridge University Press:  27 November 2003

J. Rozinek ,
Z. Vaňourková ,
M. Sedmíkova ,
V. Lánská ,
J. Petr ,
R. Rajmon  and
F. Jílek
J. Rozinek
Affiliation:
Czech University of Agriculture in Prague, Department of Veterinary Science, Prague 6, Czech Republic
Z. Vaňourková
Affiliation:
Department of Experimental Medicine, Institute for Clinical and Experimental Medicine, Prague 4, Czech Republic
M. Sedmíkova
Affiliation:
Czech University of Agriculture in Prague, Department of Veterinary Science, Prague 6, Czech Republic
V. Lánská
Affiliation:
Czech University of Agriculture in Prague, Department of Veterinary Science, Prague 6, Czech Republic
J. Petr
Affiliation:
Research Institute of Animal Production, Prague 10, Czech Republic
R. Rajmon
Affiliation:
Czech University of Agriculture in Prague, Department of Veterinary Science, Prague 6, Czech Republic
F. Jílek
Affiliation:
Czech University of Agriculture in Prague, Department of Veterinary Science, Prague 6, Czech Republic
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Abstract

The culture of pig oocytes in the presence of the calcium channel blocker verapamil (0.02 mM) resulted in the blocking of meiosis at the metaphase I stage, and only a small fraction (about 28%) of the oocytes were able to continue their maturation to the stage of metaphase II. Hence, meiotic maturation in pig oocytes is a calcium-dependent process. After isolation of the pig oocytes from their follicles, the intracellular calcium deposits in the oocyte and granulosa cells, detectable using the combined oxalate-pyroantimonate method, are depleted. The amount of calcium deposits in the oocyte and granulosa cells increased during oocyte meiotic maturation in vitro, especially in the nucleus, mitochondria, vacuoles and cytoplasm. The replenishment of calcium deposits is significantly changed under the effect of verapamil. The increase in calcium deposits in the oocyte nucleus was delayed, a much larger amount of deposits was formed in the mitochondria, and the amount of deposits in the vacuoles was demonstrably smaller. A significant peak in the accumulation of calcium deposits was observed in the cytoplasm of verapamil-treated oocytes after 16 h of in vitro culture. We propose that an altered pattern in the replenishment of calcium deposits can disturb intracellular signalling and prevent the exit of oocytes from the metaphase I stage.

Keywords

Calcium depositsMaturation in vitroOocytePigVerapamil
Type
Research Article
Information
Zygote , Volume 11 , Issue 3 , August 2003 , pp. 253 - 260
Copyright
2003 Cambridge University Press

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