Effect of Bovine Ovarian Tissue Vitrification on the Structural Preservation of Antral Follicles

Authors

  • MS Faheem,

    1. Department of Agrarian Sciences, Animal Reproduction, University of the Azores, CITA-A, Angra do Heroísmo, Portugal
    2. Animal Production Department, Faculty of Agriculture, Cairo University, Giza, Egypt
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  • I Carvalhais,

    1. Department of Agrarian Sciences, Animal Reproduction, University of the Azores, CITA-A, Angra do Heroísmo, Portugal
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  • E Baron,

    1. Department of Agrarian Sciences, Animal Reproduction, University of the Azores, CITA-A, Angra do Heroísmo, Portugal
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  • F Moreira da Silva

    Corresponding author
    • Department of Agrarian Sciences, Animal Reproduction, University of the Azores, CITA-A, Angra do Heroísmo, Portugal
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Author's address (for correspondence): Prof. Fernando Moreira da Silva, Animal Reproduction, Department of Agrarian Sciences, University of the Azores, CITA-A, 9700-042 Angra do Heroísmo, Portugal. E-mail: jsilva@uac.pt

Contents

This study was performed to evaluate the structural preservation of antral follicles after bovine ovarian tissue vitrification using histological analysis. Ovaries (n = 30) of slaughtered cows were cut into small fragments using a scalpel blade, and the ovarian tissues were randomly assigned to vitrification using 15% dimethyl sulphoxide (DMSO) and 15% ethylene glycol (EG) and fresh tissues (control) groups. For histological evaluations, fresh and post-thawing ovarian tissues were immediately fixed, serially sectioned into 5-μm sections and stained with haematoxylin and eosin (H&E). Nine serial sections per fragment were subjected for morphological assessment. The diameter of the antral follicles was determined and classified into four groups: 1 (≤1 mm), 2 (>1–2 mm), 3 (>2–3 mm) and 4 (>3–4 mm). Then, follicular morphology was evaluated in relation to atresia and categorized into seven grades: Grade A (healthy follicle); Grades B, C and D (early atresia); Grades E and F (moderate atresia); and Grade G (advanced atresia). The results revealed that small diameters of antral follicles (1 and 2 mm) were more susceptible for cryoinjury. The normal follicular morphology (Grade A) was not affected by vitrification throughout follicle diameters. Nevertheless, some damage features were monitored after vitrification. In conclusion, the morphological structure of bovine antral follicles could be successfully preserved by ovarian tissue vitrification.

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