title: Carotene cleavage activity in bovine ovarian follicles.
abstract: Carotene cleavage activity has been demonstrated in bovine ovarian follicles by incubating cell-free homogenates from granulosa cells with 15, 15'-(14)C-beta-carotene. Enzyme activity was highly dependent on the quality of follicles studied. Highest cleavage activity was found in large, preovulatory follicles. The correlation between follicular fluid concentration of vitamin A and the conversion rate obtained with the corresponding enzyme preparations was significantly positive. No correlation, however, could be shown between cleavage activity and beta-carotene, alpha-tocopherol or cholesterol. The only form of vitamin A in follicular fluid of cattle was found to be retinol. The results support the hypothesis that a local conversion of beta-carotene into vitamin A in follicular structures is responsible for the increase of the intrafollicular concentration of vitamin A during follicular development.
authors.affiliation: Institute of Physiology, Physiological Chemistry and Nutrition Physiology, Veterinary Faculty, Ludwig-Maximilians-Universität München, Veterinärstr. 13, D-8000 München 22, Germany.
authors.forename: F J
authors.initials: FJ
authors.lastname: Schweigert
authors.forename: M
authors.initials: M
authors.lastname: Wierich
authors.forename: W A
authors.initials: WA
authors.lastname: Rambeck
authors.forename: H
authors.initials: H
authors.lastname: Zucker