EFFECT OF BRILLIANT CRESYL BLUE ON IN VITRO MATURATION, FERTILIZATION, AND DEVELOPMENTAL COMPETENCE OF BOVINE OOCYTES

Document Type : Research article

Authors

1 Department of Theriogenology, Faculty of Veterinary Medicine, Mansoura University, Mansoura, 36615, Egypt

2 Articial insemination and embryo transfer Department, Animal Reproduction Institute, Agriculture Research Center (ARC)

Abstract

Brilliant cresyl blue (BCB) staining is a non-invasive technique used to select developmentally competent oocytes for in vitro embryo production. This study investigated the developmental competence of bovine oocytes with blue cytoplasm (BCB+). Ovaries were collected from healthy cows within 30 minutes’ post-slaughter. Cumulus-oocyte complexes (COCs) were aspirated from medium-sized ovarian follicles (4–8 mm), selected for quality, and incubated in Dulbecco’s phosphate-buffered saline (DPBS) supplemented with 26 µM BCB. Based on cytoplasmic staining, oocytes were classified as BCB+ (oocytes with blue cytoplasm) or BCB− (unstained cytoplasm). A third group served as an unstained control. All groups were matured in TCM-199 for 20–22 h at 38.5 °C under 5% CO₂ and 90% humidity. Following semen preparation, oocytes were co-incubated with spermatozoa for 4 hours and further cultured in TCM-199. Cleavage was assessed after 2 days, and embryo development was monitored every 48 hours for 7 days.
BCB+ exhibited significantly higher (P < 0.05) rates of cumulus expansion (91%), nuclear maturation (83%), and cleavage (56%) compared to BCB− and control groups. Blastocyst development was also significantly improved in BCB+ (27%) compared to BCB− (11%) and showed a non-significant increase over control (17%).
These findings confirm that BCB staining is an effective tool for selecting high-quality bovine oocytes for in vitro embryo production.

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Assiut Veterinary Medical Journal
Volume 71, Issue 187
October 2025
Pages 247-254

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