Maturation Competence and Chromatin Behaviour in Growing and Fully Grown Cattle Oocytes

Abstract

Chromatin configurations of cattle oocytes from different follicle sizes were classified in three chromatin categories. Early diplotenes, dictyate-like structures, more progressed diplotenes and early diakinesis and metaphases were found. In follicle group A (0.4-0.9 mm) immature diplotenes predominated (82.3%), and a rather low maturation competence was observed (12.1%). With increasing follicle size the maturation competence was improved to 47.8% metaphases II in follicle group C (3-8 mm). Impressive CMA3 positive blocks were visualized especially in early diplotenes. Heterochromatic CMA3 positive clusters surrounded the nucleolus.