Effect of follicle cells and steroidogenesis on maturation and fertilization in vitro of pig oocytes.
Follicle cell numbers, steroidogenesis, and culture conditions were manipulated in a series of experiments designed to identify their effect during in vitro maturation of pig oocytes upon meiotic cycle progression, sperm penetration and male pronuclear formation. In Experiment 1 a static culture system was used to determine the effect of follicle cell numbers on maturation. When the follicle cell number was 3.5 x 10(3) cells per complex or less, cell cycle progression to metaphase II (M-II) and male pronuclear formation were both low (< 30%). Increasing follicle cell numbers to 15 x 10(3) per complex significantly enhanced both meiotic maturation (93%) and male pronuclear formation (83%). A further 10-fold increase in follicle cell numbers (150 x 10(3)), however, reduced subsequent male pronuclear formation (33%). The purpose of Experiment 2 was to determine whether the observed follicle cell effects were influenced by the type of culture system used for oocyte maturation. Comparisons were made between both static and non-static forms of culture. Meiotic progression was significantly depressed when non-static culture systems were used for the maturation of oocyte-cumulus complexes containing low numbers of somatic cells (< 15 x 10(3) cells). However, the addition of somatic cells (follicle shells) to non-static, but not static, culture systems significantly enhanced male pronuclear formation in all groups irrespective of the number of cumulus cells in the oocyte complex. Experiment 3 investigated the effects of the steroid environment on maturation and male pronuclear formation.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Molecular Embryology, Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, England.
T
T
Nagai
J
J
Ding
R M
RM
Moor
D000818:Animals; D002452:Cell Count; D002467:Cell Nucleus; D002478:Cells, Cultured; D005260:Female; D005306:Fertilization / Q000502:physiology*; D005307:Fertilization in Vitro; D008297:Male; D008540:Meiosis; D009865:Oocytes / Q000502:physiology*; D009866:Oogenesis / Q000502:physiology*; D006080:Ovarian Follicle / Q000502:physiology*; D011374:Progesterone / Q000494:pharmacology; D013256:Steroids / Q000096:biosynthesis / Q000502:physiology*; D013552:Swine
D013256:Steroids; D011374:Progesterone