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Pavani KC, Rocha A, Oliveira E, da Silva FM, Sousa M. Novel ultrastructural findings in bovine oocytes matured in vitro. Theriogenology 2019; 143:88-97. [PMID: 31862672 DOI: 10.1016/j.theriogenology.2019.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 12/04/2019] [Accepted: 12/06/2019] [Indexed: 01/13/2023]
Abstract
The ultrastructural morphology of the bovine oocyte at different maturation stages has been previously analyzed but without detailed structural observations at the mature stage. The objective of the present study was thus to establish the ultrastructural characteristics of the mature bovine oocyte in full detail. Oocytes from Bos taurus (Holstein-Friesian) cows were aspirated from ovaries collected after being slaughtered at a local abattoir. After in vitro culture for 24 h, some of them were processed for electron microscopy. We described the ultrastructure of the zona pellucida, which presented three different regions, and novel cytoplasmic findings. There were two types of electron-lucent vesicles (heterogeneous and striated), which were suggested to give rise to lipid droplets, and presence of receptor-mediated endocytosis. In conclusion, our results indicate that although the mature bovine oocyte is devoid of evident yolk, it might be filled with an extensive lipid factory. In addition, even before fertilization, the mature oocyte seemed to absorb nutrients through receptor-mediated endocytosis, indicating active energy use or storage.
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Affiliation(s)
- K C Pavani
- Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium.
| | - A Rocha
- Department of Immuno-Physiology and Pharmacology, Center of Animal Science Studies (CECA/ICETA), Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto (UP), Rua Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal.
| | - E Oliveira
- Laboratory of Cell Biology, Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), Multidisciplinary Unit for Biomedical Research (UMIB), University of Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal.
| | - F Moreira da Silva
- Department of Reproduction, Faculty of Agrarian Sciences and Environment, Center of Investigation of Agrarian Technologies of Açores (CITA-A), Animal Reproduction, University of Açores (UAc), 9700-042, Angra do Heroísmo, Açores, Portugal.
| | - M Sousa
- Laboratory of Cell Biology, Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), Multidisciplinary Unit for Biomedical Research (UMIB), University of Porto, Rua Jorge Viterbo Ferreira, 228, 4050-313, Porto, Portugal.
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