The purpose of this study was to observein vitro-matured equine oocytes with an objective computerized technique that involves the use of a polarized light microscope (PLM) in addition to the subjective morphological evaluation obtained using a classic light microscope (LM). Equine cumulus-oocyte complexes (COCs,n = 922) were subjected to differentin vitromaturation times (24, 36 or 45 h), however, only 36-h matured oocytes were analyzed using CLM. The 36-h matured oocytes that reached maturity were parthenogenetically activated to evaluate the quality and meiotic competence. Average maturation percentages per session in groups 1, 2 and 3 (24-, 36- and 45-h matured oocytes respectively) were 29.31 ± 13.85, 47.01 ± 9.90 and 36.62 ± 5.28%, whereas the average percentages of immature oocytes per session were 28.78 ± 20.17, 7.83 ± 5.51 and 22.36 ± 8.39% respectively. The zona pellucida (ZP) birefringent properties were estimated and correlated with activation outcome. ZP thickness and retardance of the inner layer of the zona pellucida (IL-ZP) were significantly increased in immature oocytes compared with mature oocytes (P < 0.001 andP < 0.01 respectively). The comparison between parthenogenetically activated and non-activated oocytes showed a significant increase in the area and thickness of the IL-ZP in parthenogenetically activated oocytes (P < 0.01). These results show that the 36-hin vitromaturation (IVM) protocol allowed equine oocytes to reach maturity, and PLM observation of ZP can be used to distinguish mature and immature oocytes as well as activated and non-activated oocytes.
Evaluation of equine oocyte developmental competence using polarized light microscopy / A. Bertero, F. Ritrovato, F. Evangelista, V. Stabile, R. Fortina, A. Ricci, A. Revelli, L. Vincenti, T. Nervo. - In: REPRODUCTION. - ISSN 1470-1626. - 153:6(2017 Jun), pp. 775-784.
|Titolo:||Evaluation of equine oocyte developmental competence using polarized light microscopy|
BERTERO, ALESSIA (Corresponding)
|Parole Chiave:||Intracytoplasmic sperm injection; in-vitro maturation; zona-pellucida birefringence; living human oocytes; horse oocytes; chromatin configuration; cumulus morphology; meiotic spindle; parthenogenetic activation; multilaminar structure|
|Settore Scientifico Disciplinare:||Settore VET/10 - Clinica Ostetrica e Ginecologia Veterinaria|
|Data di pubblicazione:||giu-2017|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1530/REP-17-0125|
|Appare nelle tipologie:||01 - Articolo su periodico|
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