Morphology of preovulatory bovine follicles as related to oocyte maturation.
Thirty-three preovulatory bovine oocytes and their follicles were collected during the period of final maturation in normally cyclic cows. Cell density of the membrana granulosa, mitotic index of the membrana granulosa, and the occurrence of eosinophilic granulocytes around the basal membrane as well as the maturational stage of the oocyte were determined. Cell density decreased during the period of final maturation. Mitotic indices also decreased after an initial high level in the first hours of the final maturation. Eosinophilic granulocytes were only seen during the last hours of final maturation. The maturational stages of the oocytes were related to distinct maturational stages of the follicular wall as determined by morphological characteristics. We propose a scoring system for the maturity of the follicular wall based on cell density, presence of mitotic figures and the presence of eosinophilic granulocytes outside the vascular compartment.
de Loos
F A
FA
Department of Herd Health and Reproduction, Faculty of Veterinary Medicine, University of Utrecht, Yalelaan 7, 3584 CT Utrecht, The Netherlands.
Bevers
M M
MM
Dieleman
S J
SJ
Kruip
T A
TA