Nuclear maturation and structural components of nonhuman primate cumulus-oocyte complexes during in vivo and in vitro maturation.

OBJECTIVE: To compare cumulus cell structure and timing of oocyte maturation of in vitro-matured (IVM) and in vivo-matured (VVM) nonhuman primate oocytes. DESIGN: In vivo maturation and in vitro maturation of oocytes. SETTING: Animal cell culture laboratory. ANIMAL(S): Forty-eight female rhesus macaques. INTERVENTION(S): Fifteen animals were administered FSH, and aspirated oocytes were cultured in vitro for 0, 3, 6, 12, or 24 hours (IVM). Thirty-three animals were administered FSH and hCG, and oocytes were collected 3, 6, 12, or 28-30 hours after hCG (VVM). MAIN OUTCOME MEASURE(S): Nuclear maturation and microtubule scores of oocytes and actin and tubulin transzonal processes of cumulus cells. Embryo development was observed for VVM oocytes. RESULT(S): The rate of nuclear maturation was faster for IVM oocytes compared with VVM oocytes. Actin transzonal processes decreased 0-12 hours after hCG administration for VVM oocytes. Tubulin transzonal processes of IVM and VVM oocytes decreased from 0 to 24 hours and from 0 to 3 hours, respectively. Embryo development improved as VVM time increased. CONCLUSION(S): Nuclear maturation and remodeling of cumulus-oocyte complex structural components associated with in vitro maturation do not parallel those of oocyte maturation in vivo, indicating that in vitro culture conditions continue to be suboptimal.

Growth hormone and in vitro maturation of rhesus macaque oocytes and subsequent embryo development.

PURPOSE: The objective of this study was to use a nonhuman primate model to examine the effects of growth hormone (GH) on oocyte in vitro maturation (IVM). METHODS: Immunocytochemistry confirmed the presence of GH receptors in rhesus cumulus oocyte complexes and the cytoplasm of embryonic blastomeres. Recombinant human GH (r-hGH) was added to IVM medium and cumulus expansion, nuclear maturation, cytoplasmic maturation and embryo development were analyzed. RESULTS: Cumulus expansion was highest in the presence of 1 and 10 ng/ml r-hGH. The addition of r-hGH during IVM increased the percentage of embryos progressing to at least the 9-16 cell stage. In a separate study, 100 ng/ml r-hGH was supplemented to IVM and embryo culture medium and no effect was observed. CONCLUSIONS: The presence of GH receptors along with increased cumulus expansion and embryos progressing to the 9-16 cell stage supports the hypothesis that r-hGH may be involved in oocyte maturation.