Carotene cleavage activity in bovine ovarian follicles.
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.
Schweigert
F J
FJ
Institute of Physiology, Physiological Chemistry and Nutrition Physiology, Veterinary Faculty, Ludwig-Maximilians-Universität München, Veterinärstr. 13, D-8000 München 22, Germany.
Wierich
M
M
Rambeck
W A
WA
Zucker
H
H