In Vitro Maturation Group Research Articles

Influences of gonadotropin stimulation on in vitro maturation and embryogenesis of denuded mouse oocytes

Influences of gonadotropin stimulation on in vitro maturation and embryogenesis of denuded mouse oocytes

In-Vitro Maturation (IVM) of Oocytes from Unstimulated Normal Ovaries of Women with a Previous Poor Response to IVF

Objective: To evaluate the effectiveness of IVM of oocytes from unstimulated normal ovaries as a treatment option for women with a previous poor response to IVF. Design: The outcome of women undergoing IVM whose indication for treatment was a poor response during at least one previous IVF cycle was examined. A poor response to IVF was defined as the collection of ≤4 oocytes or cycle cancellation prior to oocyte retrieval because of minimal (4 follicles or fewer) ovarian response following high dose gonadotrophin stimulation. The numbers of oocytes, embryos, and embryos transferred (ET), were compared between the preceding IVF and the first IVM cycle. Materials and Methods: The IVM protocol has been described previously (Chian et al; Hum Reprod 15;1:165–170). Briefly, immature oocytes were taken from unstimulated ovaries under trans-vaginal ultrasound guidance 36 hours after the administration of hCG 10 000 IU. Following 24 hours of culture, the matured oocytes underwent ICSI. Embryos were transferred 2 days later. Results: Eight women met the study entry criteria. The median age at the time of IVM was 37.5 years (range 30 to 41) and the median number of previous IVF cycles 2.5 (range 1 to 5). IVF: The average total dose of gonadotrophins in the preceding IVF cycle was 5775 IU (range 3300 to 8400 IU). The average number of oocytes retrieved per IVF cycle commenced was 2.3; 2 cycles were cancelled after 9 and 17 days of gonadotrophin stimulation due to poor ovarian response (0 and 1 follicles produced respectively). The average number of embryos produced per IVF cycle commenced was 1.1 (range 0 to 4). Five women underwent embryo transfer with an average of 1.2 (range 1 to 2) embryos per ET. There were no pregnancies from the 8 IVF cycles commenced. IVM: At the time of immature oocyte retrieval a median of 5 (range 4 to 9) ovarian follicles were present. An average 2.3 (range 1 to 4) immature oocytes were retrieved with an average 1.7 (range 1 to 3) oocytes successfully matured. An average 1.4 (range 0 to 3) embryos were produced per IVM cycle. Six women underwent ET of an average 1.7 (range 1 to 3) embryos. There was one clinical pregnancy in the IVM group. Conclusion: When poor response to IVF is the indication for IVM the number of embryos produced and available for ET is similar with both techniques. However, IVM is simpler for the patient and does not involve ovarian stimulation with all the financial and health consequences that may be involved.

Zona drilling increases the penetrability of rat oocytes matured in vitro.

Immature rat follicular oocytes were cultured either with cumulus cells intact (CI) or cumulus-free (CF) in bovine serum albumin (BSA)- or serum-supplemented medium under conditions in which meiotic maturation occurs spontaneously. After 12 h of culture to permit in vitro maturation (IVM), the cumulus cells were stripped from the CI group. Control oocytes recovered 2-4 h after ovulation from oviducts of pregnant mare's serum gonadotropin (PMSG)-treated rats were similarly stripped of cumulus cells. Half the oocytes in each group had holes "drilled" in their zonae pellucidae by topical application of acid Tyrode's solution with a micropipette to enable bypass of the zona barrier to penetration. They were cultured for a further 14-16 h with epididymal sperm and then were assessed for sperm penetration and pronuclear formation. In a preliminary study using various concentration of sperm, 50,000 sperm/ml was identified as an appropriate concentration and was used in all subsequent experiments. For oocytes matured in serum-supplemented medium, penetration rates of non-drilled oocytes-expressed as a percentage of oocytes exposed to sperm for CF, CI, and ovulated oocytes were 10%, 34%, and 80%, respectively (p less than 0.01). Drilling significantly increased the penetration rates of both IVM groups (CF: 40%, CI: 77%) but not of ovulated oocytes (78%). Forty-one percent of non-drilled CF oocytes failed to form normal pronuclei after penetration. This was significantly higher than either the CI (0%) or ovulated (1%) groups (p less than 0.001). Drilling increased the incidence of failure to form normal pronuclei in penetrated oocytes of the CF group (64%) but not of the CI or ovulated groups.2z=