Reproduction, Fertility and Development Reproduction, Fertility and Development Society
Vertebrate reproductive science and technology
RESEARCH ARTICLE

Developmental competence of equine oocytes: impacts of zona pellucida birefringence and maternally derived transcript expression

Abdollah Mohammadi-Sangcheshmeh A D , Eva Held A D , Franca Rings A , Nasser Ghanem B , Dessie Salilew-Wondim A , Dawit Tesfaye A , Harald Sieme C , Karl Schellander A and Michael Hoelker A E
+ Author Affiliations
- Author Affiliations

A Institute of Animal Science, Animal Breeding and Husbandry Group, University of Bonn, Endenicher Allee 15, 53115 Bonn, Germany.

B Animal Production Department, Faculty of Agriculture, Cairo University, 12613 Giza, Egypt.

C Clinic for Horses, Unit of Reproductive Medicine of Clinics, University of Veterinary Medicine Hannover Foundation, 30559 Hannover, Germany.

D These authors contributed equally.

E Corresponding author. Email: michael.hoelker@itw.uni-bonn.de

Reproduction, Fertility and Development 26(3) 441-452 https://doi.org/10.1071/RD12303
Submitted: 18 September 2012  Accepted: 22 February 2013   Published: 29 April 2013

Abstract

In the present study, equine oocytes were classified into groups of presumably high and low developmental competence according to cumulus morphology, as well as oocyte ability to metabolise brilliant cresyl blue (BCB) stain. All oocytes were evaluated individually in terms of morphometry, zona pellucida birefringence (ZPB) and relative abundance of selected candidate genes. Oocytes with an expanded cumulus (Ex), representing those with presumably high developmental competence, had a significantly thicker zona (18.2 vs 17.3 µm) and a significantly higher ZPB (64.6 vs 62.1) than oocytes with a compacted cumulus (Cp). Concurrently, oocytes classified as highly developmentally competent (BCB+) had a significantly thicker zona (18.8 vs 16.1 µm) and significantly higher ZPB (63.1 vs 61.3) compared with oocytes classified as having low developmental competence. Expression of TFAM, STAT3 and CKS2 was significantly higher in Ex compared with Cp oocytes, whereas expression of COX1, ATPV6E and DNMT1 was lower. Together, the data reveal that developmentally competent equine oocytes are larger in size, have higher ZPB values and exhibit a typical genetic signature of maternally derived transcripts compared with oocytes with lower in vitro developmental competence.

Additional keywords: gene expression profile, in vitro production.


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